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                                               Filed pursuant to Rule 424(b)(3)
                                               Registration No. 333-70333
 
                             P R O S P E C T U S
 
                               [PLANTRONICS LOGO]
 
                      UP TO 77,258 SHARES OF COMMON STOCK
 
                WHICH PLANTRONICS MAY SELL UNDER THIS PROSPECTUS
 
     Plantronics, Inc. may offer and sell up to 77,258 shares of Plantronics
common stock to you under this prospectus. Plantronics will only sell these
shares if, and to the extent, you exercise your options to purchase the shares
of Plantronics common stock.
 
     If and when you exercise the options, in whole or in part, Plantronics will
issue shares to you at a per share price equal to the per share exercise price
under the option agreements which govern the options. Examine the option
agreements which cover the options you wish to exercise in order to determine
the applicable per share exercise price.
 
     INVESTING IN THE COMMON STOCK INVOLVES RISKS WHICH ARE DESCRIBED IN THE
"RISK FACTORS" SECTION BEGINNING ON PAGE 3 OF THIS PROSPECTUS.
 


                                        PER SHARE PRICE:    TOTAL PRICE:
                                        ----------------    ------------
                                                   
                     77,258 options:         $ 0.90          $69,532.20

 
     Plantronics common stock is listed on the New York Stock Exchange under the
ticker symbol "PLT". On February 4, 1999, the last reported sale price on the
NYSE of one share of Plantronics common stock was $71 1/2.
 
     Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.
 
                           -------------------------
 
                The date of this prospectus is February 4, 1999
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                               TABLE OF CONTENTS
 


                                                              PAGE
                                                              ----
                                                           
Plantronics' Address........................................    2
Forward-Looking Statements..................................    2
Risk Factors................................................    3
Information Incorporated by Reference.......................   12
How to Get Information About Plantronics....................   12
Legal Matters...............................................   13
Experts.....................................................   13

 
                              PLANTRONICS' ADDRESS
 
     Plantronics' principal executive offices are located at 345 Encinal Street,
Santa Cruz, California 95060. Plantronics' telephone number at that location is
(831) 426-5858.
 
                           FORWARD-LOOKING STATEMENTS
 
     This prospectus and the documents incorporated herein by reference contain
forward-looking statements. Plantronics bases these statements on its current
expectations, estimates and projections about its industry. Either the beliefs
of management, or assumptions made by management, form the basis for those
expectations, estimates and projections. The safe harbor created by Section 27A
of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of
1934 generally protects Plantronics from liability for these statements. You can
often recognize such forward-looking statements by words such as "anticipates,"
"expects," "intends," "plans," "believes," "seeks," "estimates," variations of
such words, and similar expressions.
 
     These forward-looking statements do not guarantee future performance and
are subject to risks, uncertainties and assumptions that are difficult to
predict. The Risk Factors section immediately following this paragraph sets
forth some of such risks and uncertainties. The documents incorporated by
reference may also set forth risks and uncertainties. These risks and
uncertainties could cause actual results to differ materially and adversely from
those discussed in the forward-looking statements. Plantronics undertakes no
obligation to publicly update any of these forward-looking statements to reflect
new information or future events.
 
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                                  RISK FACTORS
 
     Investing in our common stock will provide you with an equity ownership
interest in Plantronics. As a Plantronics shareholder, you may be subject to
risks inherent in our business. The performance of your shares will reflect the
performance of our business relative to, among other things, our competition,
general economic and market conditions and industry conditions. The value of
your investment may increase or decline and could result in a loss. You should
carefully consider the following factors as well as other information contained
in this prospectus before deciding to invest in our common stock.
 
DEPENDENCE ON CALL CENTER MARKET SEGMENT
 
     We have historically derived, and continue to derive, a substantial
majority of our net sales from the call center market segment. This market
segment has grown significantly in recent years as new call centers have
proliferated and existing call centers have expanded. While we believe this
market segment is continuing to grow, in the future this growth could slow or
revenues from this market segment could decline due to various factors. For
example, technological advances such as automated interactive voice response
systems could reduce or eliminate the need for call center agents in certain
applications. In addition, consumer resistance to telemarketing could adversely
affect growth in the call center market segment. Due to our reliance on the call
center market segment, we will be affected more by changes in the rate of call
center establishment and expansion and the communications products that call
center agents use than would a company serving a broader market. We believe that
our sales growth to date in fiscal 1999 may have been favorably affected by call
centers upgrading their automatic call distribution systems in order to be year
2000 compliant. Since our products are sometimes bundled with new call
distribution systems, this may have accelerated some headset sales. If this has
occurred, it could adversely affect our net sales in future periods, once call
centers have completed their system upgrades. Any decrease in the demand for
call centers and related headset products could cause a decrease in the demand
for our products, which would materially adversely affect our business,
financial condition and results of operations.
 
FAILURE OF THE OFFICE, MOBILE, COMPUTER AND RESIDENTIAL MARKET SEGMENTS TO
DEVELOP
 
     While the call center market segment is still the most significant part of
our business, we believe that our future prospects will depend in large part on
the growth in demand for headsets in the office, mobile, computer and
residential market segments. These communications headset market segments are
relatively new and undeveloped. Moreover, we do not have extensive experience in
selling headset products to customers in these market segments. If the demand
for headsets in these market segments fails to develop, or develops slower than
we currently anticipate, or if we are unable to effectively market our products
to customers in these market segments, it would have a material adverse effect
on the potential demand for our products and on our business, financial
condition and results of operations.
 
OUR QUARTERLY OPERATING RESULTS MAY FLUCTUATE SIGNIFICANTLY
 
     Our quarterly results of operations may vary significantly in the future
for a variety of reasons, including the following:
 
     - changes in demand for our products;
 
     - timing and size of orders from customers;
 
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     - cancellations or delays of deliveries of components and subassemblies by
       our suppliers;
 
     - variances in the timing and amount of engineering and operating expenses;
 
     - distribution channel volume variations;
 
     - delays in shipments of our products;
 
     - product returns and customer credits;
 
     - new product introductions by us or our competitors;
 
     - entrance of new competitors;
 
     - increases in the costs of our components and subassemblies;
 
     - price erosion;
 
     - changes in the mix of products sold by us;
 
     - seasonal fluctuations in demand; and
 
     - general economic conditions.
 
     Each of the above factors is difficult to forecast and thus could have a
material adverse effect on our business, financial condition and results of
operations.
 
     We generally ship most orders during the quarter in which they are
received, and, consequently, we do not have a significant backlog of orders. As
a result, quarterly net sales and operating results depend primarily on the
volume and timing of orders received during the quarter. It is difficult to
forecast orders for a given quarter. Since a large portion of our operating
expenses, including rent, salaries and certain manufacturing expenses, are fixed
and difficult to reduce or modify, if net sales do not meet our expectations,
our business, financial condition and results of operations could be materially
adversely affected.
 
     Our operating results can also vary substantially in any period depending
on the mix of products sold and the distribution channels through which they are
sold. In the event that sales of lower margin products or sales through lower
margin distribution channels in any period represent a disproportionate share of
total sales during such period, our operating results would be materially
adversely affected.
 
     We believe that period-to-period comparisons of our operating results are
not necessarily meaningful and should not be relied upon as indicative of future
operating results. In addition, our operating results in a future quarter or
quarters may fall below the expectations of securities analysts or investors,
and, as a result, the price of our common stock might fall.
 
WE MUST MATCH PRODUCTION TO DEMAND
 
     Historically, we have seen steady increases in customer demand for our
products and have generally been able to increase production to meet that
demand. However, the demand for our products is dependent on many factors and
such demand is inherently difficult to forecast. Significant unanticipated
fluctuations in demand could cause the following operating problems, among
others:
 
     - If demand increases beyond that forecasted, we would have to rapidly
       increase production. We depend on suppliers to provide additional volumes
       of components
 
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       and subassemblies, and, therefore, might not be able to increase
       production rapidly enough to meet unexpected demand. This could cause us
       to fail to meet customer expectations. There could be short-term losses
       of sales while we are trying to increase production. If customers turn to
       competitive sources of supply to meet their needs, there could be a
       long-term impact on our revenues.
 
     - Rapid increases in production levels to meet unanticipated demand could
       result in higher costs for components and subassemblies and higher
       overtime costs and other expenses. These higher expenditures could lower
       our profit margins. Further, if production is increased rapidly, there
       may be decreased manufacturing yields, which may also lower our margins.
 
     - If forecasted demand does not develop, we could have excess production or
       excess capacity. Excess production could result in higher inventories of
       finished products, components and subassemblies. If we were unable to
       sell these inventories, we would have to write off some or all of our
       inventories of obsolete products and unusable components and
       subassemblies. Excess manufacturing capacity could lead to higher
       production costs and lower margins.
 
Any of the foregoing problems could materially adversely affect our business,
financial condition and results of operations.
 
WE DEPEND ON OUR SUPPLIERS
 
     We buy components and subassemblies from a variety of suppliers and
assemble them into finished products. The cost, quality, and availability of
such components are essential to the successful production and sale of our
products. Obtaining components and subassemblies entails various risks,
including the following:
 
     - Prices of components and subassemblies may rise. If this occurs and we
       are not able to pass these increases on to our customers or to achieve
       operating efficiencies that would offset the increases, it would have a
       material adverse effect on our business, financial condition and results
       of operations.
 
     - We obtain certain subassemblies and components from single suppliers, and
       alternate sources for these items are not readily available. To date, we
       have experienced only minor interruptions in the supply of these
       components and subassemblies, none of which has significantly affected
       our results of operations. However, an interruption in supply from any of
       our single source suppliers in the future would materially adversely
       affect our business, financial condition and results of operations.
 
     - Most of our suppliers are not obligated to continue to provide us with
       components and subassemblies. Rather, we buy most components and
       subassemblies on a purchase order basis. If our suppliers experience
       increased demand or shortages, it could affect deliveries to us. In turn,
       this would affect our ability to manufacture and sell products that are
       dependent on those components and subassemblies. This would materially
       adversely affect our business, financial condition and results of
       operations.
 
THE HEADSET MARKET IS HIGHLY COMPETITIVE
 
     The market for our products is highly competitive. We compete with a
variety of companies in various segments of the communications headset market.
In the call center segment, the largest market segment in which we compete, our
two largest competitors,
 
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GN Netcom and ACS Wireless, Inc., recently merged to form a single company.
Although it is unclear how this merger will affect us, the merged entity will
have a broader product offering and greater marketing presence than either of
the two entities had separately. Moreover, the economies of scale that may
result from the merger could lead to increased pricing pressures in our market.
 
     We also anticipate that we will face additional competition from companies
that currently do not offer communications headsets. This is particularly true
in the office, mobile, computer and residential market segments. As these market
segments mature, we will face increased competition from consumer electronics
companies and other companies that currently manufacture and sell mobile phones
or computer peripheral equipment. These new competitors are likely to be larger,
offer broader product lines, bundle or integrate with other products
communications headset tops and bases manufactured by them or others, offer
products containing bases that are incompatible with our headset tops and have
substantially greater financial, marketing and other resources than we do.
 
     We believe that important competitive factors for us are product
reliability, product features, customer service and support, reputation,
distribution, ability to meet delivery schedules, warranty terms, product life
and price. If we do not compete successfully with respect to any of these or
other factors it could materially adversely affect our business, financial
condition and results of operations. If we do not successfully develop and
market products that compete successfully with those of our competitors it would
materially adversely affect our business, financial condition and results of
operations.
 
NEW PRODUCT DEVELOPMENT IS RISKY; WE MUST RESPOND TO CHANGING CUSTOMER
REQUIREMENTS AND TECHNOLOGIES
 
     Our product development efforts historically have been directed toward
enhancement of existing products and development of new products that capitalize
on our core capabilities. The success of new product introductions is dependent
on several factors, including the proper selection of new product features,
timely completion and introduction of new product designs, cost-effective
manufacture of such products, quality of new products and market acceptance. To
be successful in the future, we must develop new products, qualify these new
products, successfully introduce these products to the market on a timely basis,
and commence and sustain low-cost, volume production to meet customers' demands.
Although we attempt to determine the specific needs of headset users in our
target market segments, because almost all of our sales are indirect, we may not
always be able to timely and accurately predict end-user requirements. As a
result, our products may not be timely developed, designed to address current or
future end-user requirements, offered at competitive prices or accepted, which
could materially adversely affect our business, financial condition and results
of operations. Moreover, we generally incur substantial research and development
costs before the technical feasibility and commercial viability of a new product
can be ascertained. Accordingly, revenues from new products may not be
sufficient to recover the associated development costs.
 
     Historically, the technology used in lightweight communications headsets
has evolved slowly. New products have primarily offered stylistic changes and
quality improvements, rather than significant new technologies. We anticipate
that the technology used in hands-free communications devices, including our
products, will begin to evolve more rapidly in the future. We believe that this
is particularly true of the office, mobile and residential market segments,
which may require us to develop new headset technologies to support cordless and
wireless operation and to interface with new communications and computing
 
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devices. As a result, our success depends upon our ability to enhance existing
products, to respond to changing market requirements, and to develop and
introduce in a timely manner new products that keep pace with technological
developments. If we are unable to develop and introduce enhanced products or new
products in a timely manner in response to changing market conditions or
customer requirements, it will materially and adversely affect our business,
financial condition and results of operations.
 
WE DEPEND ON OUR DISTRIBUTION CHANNELS
 
     We sell substantially all of our products through distributors, original
equipment manufacturers ("OEMs"), retailers and telephony service providers. Our
existing relationships with these parties are nonexclusive and can be terminated
by either party without cause. Our channel partners also sell or can potentially
sell products offered by our competitors. To the extent that our competitors
offer our channel partners more favorable terms, such partners may decline to
carry, de-emphasize or discontinue carrying our products. In the future, we may
not be able to retain or attract a sufficient number of qualified channel
partners. Further, such partners may not recommend, or continue to recommend,
our products. The inability to establish or maintain successful relationships
with distributors, OEMs, retailers and telephony service providers or to expand
our distribution channels could materially adversely affect our business,
financial condition or results of operations.
 
WE DEPEND ON S. KENNETH KANNAPPAN AND OTHER KEY PERSONNEL
 
     Our success depends to a significant extent upon the services of a limited
number of executive officers and other key employees. On January 4, 1999, S.
Kenneth Kannappan was promoted to Chief Executive Officer of our company,
succeeding Robert S. Cecil in that capacity, and was appointed to our Board of
Directors. Mr. Kannappan joined our company in February 1995 and has held a
number of executive management positions, including President and Chief
Operating Officer. Mr. Kannappan has been assuming increasing responsibilities
for our day-to-day operations since his March 1998 appointment as President and
Chief Operating Officer. The unanticipated loss of the services of Mr. Kannappan
or one or more of our other executive officers or key employees could have a
material adverse effect upon our business, financial condition and results of
operations.
 
     We also believe that our future success will depend in large part upon our
ability to attract and retain additional highly skilled technical, management,
sales and marketing personnel. Competition for such personnel is intense. We may
not be successful in attracting and retaining such personnel, and, our failure
to do so could have a material adverse effect on our business, operating results
or financial condition.
 
CITICORP VENTURE CAPITAL RETAINS SIGNIFICANT CONTROL
 
     After this offering, our largest stockholder, Citicorp Venture Capital,
Ltd. ("CVC"), will beneficially own 4,509,168 shares of our common stock
(excluding any shares that may be owned by Citigroup Foundation or by employees
or affiliates of CVC or Citigroup Foundation), which will represent
approximately 26.3% of the outstanding common stock. We also have an agreement
with CVC under which it is entitled to have up to three of its designees serve
on our Board of Directors, depending on the level of CVC's continuing stock
ownership. Messrs. Robert F.B. Logan, M. Saleem Muqaddam and John Mowbray O'Mara
are currently serving as CVC's designees under that agreement. Accordingly, CVC
has the ability to exert substantial influence on the full Board of Directors,
which currently
 
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consists of eight members. In addition, our bylaws contain provisions that
require a supermajority vote of the Board of Directors to approve certain
transactions, including amendments of our Certificate of Incorporation and
bylaws, mergers and sales of substantial assets, acquisitions of other companies
and sales of capital stock. These provisions may have the effect of giving a
small number of directors the ability to block such transactions.
 
FUTURE SALES OF OUR COMMON STOCK BY CITICORP VENTURE CAPITAL, CITIGROUP
FOUNDATION, MR. AND MRS. CECIL OR MANAGEMENT MAY DEPRESS OUR STOCK PRICE
 
     Upon completion of this offering, we will have outstanding 17,159,454
shares of common stock (based upon shares outstanding as of December 31, 1998),
assuming no exercise of the underwriters' over-allotment option and no exercise
of outstanding options after December 31, 1998 other than exercises by Mr. and
Mrs. Cecil as described elsewhere in this prospectus. All of these shares will
be freely tradable except for 4,509,168 shares held by CVC, 193,548 shares held
by Citigroup Foundation, and 433,254 shares held by our executive officers and
directors. These 5,135,970 shares, as well as an additional 2,013,118 shares
subject to outstanding stock options at December 31, 1998 held by executive
officers, directors and Mrs. Cecil, are subject to lockup agreements with the
underwriters and cannot be sold for a period of 90 days after the offering
without the prior written consent of Merrill Lynch, Pierce, Fenner & Smith
Incorporated. In addition, the holders of these shares or options may only sell
their shares in reliance on Rule 144 under the Securities Act of 1933, as
amended (the "Securities Act"), or pursuant to an effective registration
statement filed with the Securities and Exchange Commission. Certain of our
current stockholders, including CVC, Citigroup Foundation and certain of our
officers, directors and key employees, also have contractual rights to require
Plantronics to register their shares for public sale. Sales of a substantial
number of shares of common stock in the public market following the offering, as
well as sales of shares issued upon exercise of stock options, by any of the
officers, directors or other stockholders mentioned above could adversely affect
the prevailing market price of the common stock and impair our ability to raise
capital through the sale of equity securities.
 
RISKS ASSOCIATED WITH OUR FOREIGN OPERATIONS
 
     Approximately 30.7% and 30.2% of our net sales in fiscal 1998 and the six
months ended September 30, 1998, respectively, were derived from customers
outside the United States. In addition, we conduct substantially all of our
headset assembly operations in our manufacturing facility located in Mexico, and
we obtain most of the components and subassemblies used in our products from
various foreign suppliers. The inherent risks of international operations,
particularly in Mexico, could materially adversely affect our business,
financial condition and results of operations. The types of risks faced in
connection with international operations and sales include:
 
     - cultural difference in the conduct of business;
 
     - greater difficulty in accounts receivable collection;
 
     - unexpected changes in regulatory requirements;
 
     - tariffs and other trade barriers;
 
     - economic and political conditions in each country;
 
     - management and operation of an enterprise spread over various countries;
       and
 
     - burden of complying with a wide variety of foreign laws.
 
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     A significant portion of our business is conducted in currencies other than
the U.S. dollar. As a result, fluctuations in exchange rates creates risk to us
in both the sale of our products and our purchase of supplies. Fluctuations in
the value of the currencies in which we conduct our business relative to the
U.S. dollar have caused and will continue to cause currency transaction gains
and losses. Although we do not currently engage in any hedging activities to
mitigate exchange rate risks, we continually evaluate programs to reduce our
foreign currency exposure. However, there can be no assurance that we will not
continue to experience currency losses in the future, nor can we predict the
effects of future exchange rate fluctuations on future operating results. To the
extent that sales to our foreign customers increase or transactions in foreign
currencies increase, our business, financial condition and results of operations
could be materially adversely affected by exchange rate fluctuations. In
addition, we cannot predict the potential consequences to our business of the
adoption of the Euro as a common currency in Europe.
 
WE DEPEND ON OUR PRINCIPAL MANUFACTURING FACILITY
 
     Substantially all of our manufacturing operations are currently performed
in a single facility in Tijuana, Mexico. A fire, flood or earthquake, political
unrest or other disaster or condition affecting our facility could have a
material adverse effect on our business, financial condition and results of
operations. While we have developed a disaster recovery plan and believe we are
adequately insured with respect to this facility, we may not be able to
implement the plan effectively or on a timely basis or recover under applicable
insurance policies.
 
FAILURE OF ELECTRONIC SYSTEMS TO RECOGNIZE THE YEAR 2000
 
     Many existing electronic systems, including computer systems, use only the
last two digits to refer to a year. Therefore, these systems may recognize a
date using "00" as 1900 rather than the year 2000. If not corrected, many
computer and other electronic applications and systems could fail or create
erroneous results when addressing dates on and after January 1, 2000. Our
products do not address or utilize dates in their operation, and, accordingly,
our products should not fail due to the year 2000 problem. However, we use and
depend on information technology systems (including business information
computer systems and design and manufacturing computer systems) and other
machinery and equipment that includes embedded date sensitive technology. We
also depend on the proper functioning of date sensitive electronic systems of
third parties, such as customers and suppliers. The failure of any of these
systems to appropriately interpret the year 2000 could have a material adverse
effect on our business, financial condition and results of operations. We are
undertaking efforts to ensure that our business systems and those of our
suppliers and customers are compliant with the requirements of the year 2000.
However, our year 2000 program may not be effective or we may not be able to
implement it in a timely and cost-effective manner. Our year 2000 efforts may
not, therefore, ensure against disruptions caused by the approach or advent of
the year 2000. The year 2000 problem is potentially very widespread, and it is
not possible to determine all the potential risks that we may face. Our
inability to remedy our own year 2000 problems or the failure of third parties
to do so may cause business interruptions or shutdowns, financial loss,
regulatory actions, harm to our reputation and exposure to liability.
 
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RISKS OF INADEQUATE PROTECTION OF INTELLECTUAL PROPERTY AND INFRINGEMENT OF
RIGHTS OF OTHERS
 
     Our success will depend in part on our ability to protect our proprietary
technology. We rely primarily on a combination of nondisclosure agreements and
other contractual provisions as well as patent, trademark, trade secret, and
copyright laws to protect our proprietary rights. We currently hold 33 United
States patents and additional foreign patents and intend to continue to seek
patents on our inventions when we believe it to be appropriate. The process of
seeking patent protection can be lengthy and expensive. Patents may not be
issued in response to our applications, and patents that are issued may be
invalidated, circumvented or challenged by others. If we are required to enforce
our patents or other proprietary rights through litigation, the costs and
diversion of management's attention could be substantial. In addition, the
rights granted under any patents may not provide us competitive advantages or be
adequate to safeguard and maintain our proprietary rights. Moreover, the laws of
certain countries do not protect our proprietary rights to the same extent as do
the laws of the United States. If we do not enforce and protect our intellectual
property rights, it could materially adversely affect our business, financial
condition and results of operations.
 
     From time to time, third parties, including our competitors, may assert
patent, copyright and other intellectual property rights against us. Such
claims, if they are asserted, could result in costly litigation and diversion of
management's attention. In addition, we may not ultimately prevail in any such
litigation or be able to license any valid and infringed patents from such third
parties on commercially reasonable terms, if at all. Any infringement claim or
other litigation against us could materially adversely affect our business,
financial condition and results of operations.
 
PRODUCT LIABILITY EXPOSURE
 
     The use of our products exposes us to the risk of product liability claims.
Product liability claims have in the past been, and are currently being,
asserted against us. None of the previously resolved claims have materially
affected our business, financial condition or results of operations, nor do we
believe that any of the pending claims will have such an effect. Although we
maintain product liability insurance, the coverage provided under our policies
could be unavailable or insufficient to cover the full amount of any such claim.
Therefore, successful product liability claims brought against us could have a
material adverse effect upon our business, financial condition and results of
operations.
 
OUR STOCK PRICE MAY BE VOLATILE
 
     The market price for our common stock may be affected by a number of
factors, including the announcement of new products or product enhancements by
us or our competitors, the loss of services of one or more or our executive
officers or other key employees, quarterly variations in our or our competitors'
results of operations, changes in earnings estimates or recommendation by
securities analysts, developments in our industry, sales of substantial numbers
of shares of our common stock in the public market, general market conditions
and other factors, including factors unrelated to our operating performance or
the operating performance of our competitors. In addition, stock prices for many
companies in the technology sector have experienced wide fluctuations that have
often been unrelated to the operating performances of such companies. Such
factors and fluctuations, as well as general economic, political and market
conditions, such as recessions, may materially adversely affect the market price
of our common stock.
 
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ENVIRONMENTAL MATTERS
 
     We are subject to various federal, state, local and foreign environmental
laws and regulation, including those governing the use, discharge and disposal
of hazardous substances in the ordinary course of our manufacturing process.
Although we believe that our current manufacturing operations comply in all
material respects with applicable environmental laws and regulations,
environmental legislation has been enacted and may in the future be enacted or
interpreted to create environmental liability with respect to our facilities or
operations. We have included in our financial statements a reserve of $1.5
million for possible environmental remediation of the site of one of our
previous businesses. While no claims have been asserted against us in connection
with this matter, such claims could be asserted in the future and any liability
that might result could exceed the amount of the reserve.
 
EFFECTS OF ANTITAKEOVER PROVISIONS
 
     Our Board of Directors has the authority to issue preferred stock and to
determine the price, rights, preferences, privileges and restrictions, including
voting and conversion rights, of those shares without any further vote or action
by the stockholders. The issuance of our preferred stock could have the effect
of making it more difficult for a third party to acquire us. In addition, we are
subject to the antitakeover provisions of Section 203 of the Delaware General
Corporation Law, which could also have the effect of delaying or preventing our
acquisition by a third party. Further, certain provisions of our Certificate of
Incorporation and bylaws could delay or make more difficult a merger, tender
offer or proxy contest, which could adversely affect the market price of our
common stock.
 
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                     INFORMATION INCORPORATED BY REFERENCE
 
     This prospectus incorporates by reference the following documents and
information, all of which Plantronics has filed in the past with the SEC:
 
     - Plantronics' Annual Report on Form 10-K for the fiscal year ended March
       28, 1998.
 
     - Plantronics' Quarterly Report on Form 10-Q for the quarterly period ended
       June 27, 1998.
 
     - Plantronics' Quarterly Report on Form 10-Q for the quarterly period ended
       September 26, 1998.
 
     - Plantronics' Current Report on Form 8-K dated January 12, 1999.
 
     - Plantronics' Quarterly Report on Form 10-Q for the quarterly period ended
       December 26, 1998, as amended.
 
     - Item 1 of Plantronics' Registration Statement on Form 8-A, filed on
       December 20, 1993, as amended on January 14, 1994 and November 7, 1997
       (which in turn incorporates by reference the description of Plantronics'
       common stock set forth in Plantronics' Registration Statement on Form S-1
       (Reg. No. 33-70744), filed on October 20, 1993, as amended by Amendment
       No. 1, filed on November 30, 1993, Amendment No. 2, filed on December 27,
       1993, and Amendment No. 3, filed on January 18, 1994).
 
     All documents, if any, which Plantronics subsequently files under Section
13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of this
prospectus but prior to the termination of the offering described in this
prospectus shall be deemed to be incorporated by reference in this prospectus
and to be part of this prospectus from the date of filing of such documents.
 
     Plantronics will provide without charge to each person to whom a copy of
this prospectus is delivered, upon written or oral request, a copy of the
information that has been or may be incorporated by reference in this
prospectus, other than exhibits to such documents. Direct any request for such
copies to John A. Knutson, Vice President - Legal, Senior General Counsel and
Secretary, Plantronics, Inc., 345 Encinal Street, Santa Cruz, California 95060,
Tel: (831) 426-5858.
 
                    HOW TO GET INFORMATION ABOUT PLANTRONICS
 
     Plantronics is subject to the informational requirements of the Exchange
Act and therefore files reports, proxy and information statements and other
information with the SEC. You can inspect many of such reports, proxy and
information statements and other information on the SEC's internet website at
http://www.sec.gov.
 
     You can also inspect and copy such reports, proxy and information
statements and other information at the SEC's Public Reference Room, 450 Fifth
Street, N.W., Washington, D.C. 20549. You can obtain information on the
operation of the Public Reference Room by calling the SEC at Tel:
1-800-SEC-0330. You can also inspect and copy such reports, proxy and
information statements and other information may also be inspected and copied at
the following Regional Offices of the SEC: New York Regional Office, Seven World
Trade Center, Suite 1300, New York, New York 10048; and Chicago Regional Office,
Northwest Atrium Center, 500 West Madison Street, Suite 1400,
 
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Chicago, Illinois 60661. Plantronics' common stock is listed on the NYSE, and
you can inspect such reports, proxy and information statements and other
information at the offices of the NYSE, 20 Broad Street, New York, New York
10005.
 
     This prospectus constitutes part of a registration statement on Form S-3
filed by Plantronics with the SEC under the Securities Act. This prospectus does
not contain all of the information set forth in the registration statement. For
further information with respect to Plantronics and the shares, you should refer
to the registration statement either at the SEC's website or at the addresses
set forth in the preceding paragraph. Statements in this prospectus concerning
any document filed as an exhibit to this prospectus are not necessarily
complete, and, in each instance, you should refer to the copy of such document
which has been filed as an exhibit to the registration statement. Each such
statement is qualified in its entirety by such reference.
 
     No one is authorized to give any information or to make any representations
not contained in this prospectus in connection with any offering made by this
prospectus. If given or made, you must not rely on such information or
representations as having been authorized by Plantronics or by any other person.
This prospectus does not constitute an offer to sell or a solicitation of an
offer to buy any security other than the shares offered hereby. This prospectus
also does not constitute an offer to sell or a solicitation of an offer to buy
any of the shares offered hereby to any person in any jurisdiction in which it
is unlawful to make such an offer or solicitation. Neither delivery of this
prospectus, nor any sale or offer to sell shares hereunder, shall under any
circumstances create any implication that there has been no change in the
affairs of Plantronics since the date of this prospectus or that the information
contained in this prospectus is correct as of any time subsequent to the date of
this prospectus.
 
                                 LEGAL MATTERS
 
     The validity of the shares of common stock offered hereby will be passed
upon for Plantronics by Wilson Sonsini Goodrich & Rosati, Professional
Corporation, Palo Alto, California.
 
                                    EXPERTS
 
     The financial statements incorporated in this prospectus by reference to
Plantronics' Annual Report on Form 10-K for the fiscal year ended March 28, 1998
have been so incorporated in reliance on the report of PricewaterhouseCoopers
LLP, independent accountants, given on the authority of such firm as experts in
auditing and accounting.
 
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