EXHIBIT 99

Investors and Press Contact:
Kathy Bayless
Chief Financial Officer
(408) 576-2000
ir_web@komag.com

Komag Reports First Quarter of 2004 Earnings

FOR IMMEDIATE RELEASE

SAN JOSE, Calif., April 28, 2004 — Komag, Incorporated (Nasdaq: KOMG), the largest independent supplier of thin-film media for disk drives, today announced earnings of $18.0 million, and diluted earnings per share of $0.65 for the first quarter of 2004.

First quarter 2004 revenue, net income and earnings per share were $123.6 million, $18.0 million and $0.65 compared to $118.2 million, $16.4 million and $0.65 in the fourth quarter of 2003. In the first quarter of 2003, the Company reported revenue of $105.5 million, net income of $5.1 million and earnings per share of $0.21.

In the first quarter of 2004, revenue increased 5% from the prior quarter and 17% from the first quarter of 2003. Finished disk shipments were 19.2 million in the first quarter of 2004 compared to 19.3 million in the prior quarter and 16.7 million a year ago. Other disk revenue was $9.6 million in the first quarter of 2004 compared to $8.4 million in the fourth quarter of 2003 and $12.4 million a year ago.

Operating income in the first quarter of 2004 was $20.1 million compared to $21.0 million in the fourth quarter of 2003 and $9.2 million in the year ago quarter or an operating margin of 16%, 18% and 9%, respectively.

In January 2004, the Company completed the sale of 3.525 million shares of common stock and issued $80.5 million of 2.0% Convertible Subordinated Notes. Total net proceeds from the offerings were approximately $144.0 million. In the first quarter of 2004, the Company repaid in full its Senior Secured Notes and other notes with the proceeds from the offerings. The total outstanding balance of the Senior Secured Notes and the other notes was $116.0 million at the end of the fourth quarter of 2003. At the end of the first quarter of 2004, the Company’s only outstanding debt was the new $80.5 million of 2.0% Convertible Subordinated Notes.

The Company ended the first quarter of 2004 with $80.9 million of cash.

First Quarter Review

Sales to Maxtor, Hitachi Global Storage Technologies, Western Digital, and Seagate accounted for 45%, 21%, 19% and 8% of total revenue in the first quarter of 2004, respectively. Finished disk shipments for desktop and consumer applications together represented 89% of Komag’s first quarter of 2004 unit shipment volume. The remaining finished disk shipments (11%) in the first quarter of 2004 were disks for high-end server (enterprise) drives.

In February 2004, the Company completed the purchase of a substrate manufacturing facility in Malaysia from Trace Storage Technology Corporation (Trace) for $10.0 million to support the increasing finished unit capacity and allow the Company to become a substrate supplier to Trace.

As previously announced, the Company is in the process of expanding its finished unit capacity within its current manufacturing facilities from 20 million per quarter to approximately 24 to 25 million per quarter. The current plan is to have the full new capacity available to support the seasonally stronger second half of 2004.

Total capital spending in the first quarter of 2004 was $23.7 million, which included a portion of the capital expenditures for the capacity expansion as well as the $10.0 million purchase price of the substrate facility.

T.H. Tan, Komag’s chief executive officer announced, “We are very pleased to begin 2004 with a stronger balance sheet due to the completion of our debt and equity offerings and the continuing strength of our operating performance. The initial operations of the new substrate facility are proceeding well and our capacity expansion is in progress. We also expanded our unit shipments for high-end server (enterprise) drives and high-performance multi platter drives.”

The Company uses a 52-53 week fiscal year ending on the Sunday closest to December 31. The Company’s 2004 fiscal year contains 53 weeks. The additional week was included in the Company’s first quarter of 2004. As such, the first quarter of 2004 was comprised of 14 weeks and all other quarters in 2004 will include 13 weeks.

Business Outlook

As previously discussed, the first quarter of 2004 included 14 weeks. Based on current customer demand, which reflects the traditional seasonally soft second quarter combined with returning to the normal 13 week quarter, the Company expects total revenue for the second quarter of 2004 to be down approximately 15% from the first quarter of 2004. Also, with the current seasonal market conditions, the Company plans to reduce production levels and perform its normal annual preventative maintenance at its finished unit manufacturing facilities in the second quarter of 2004. With the reduced sales and production levels, both operating and net profit margins are expected to be between 9% and 12%.

About Komag

Founded in 1983, Komag is the world’s largest independent supplier of thin-film disks, the primary high-capacity storage medium for digital data. Komag leverages the combination of its world-class U.S. research and development center and Malaysian manufacturing operations to produce disks that meet the high-volume, stringent quality, low cost and demanding technology needs of its customers. By enabling rapidly improving storage density at ever-lower cost per gigabyte, Komag seeks to create extraordinary value for consumers of computers, enterprise storage systems and electronic appliances such as digital video recorders, game boxes and consumer electronic storage systems.

For more information about Komag, visit Komag’s Internet home page at http://www.komag.com. The Investors section of the website provides a variety of financial and investor information, including an investor presentation. To request an investor packet, call Komag’s Investor Relations at 408-576-2901.

Forward-Looking Statements

This press release contains certain “forward-looking” statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are subject to the safe harbors created thereby. These statements represent the Company’s current judgment and include, but are not limited to the belief that

finished unit capacity will increase to approximately 24 to 25 million and be available for the traditionally stronger second half of 2004, that production levels will decrease in the second quarter of 2004, that revenue in the second quarter of 2004 will be down approximately 15% from revenue in the first quarter of 2004 and that the operating and net profit margins are expected to both be between 9% and 12%. The Company’s actual results for future periods could differ materially from those projected in such forward-looking information. Factors that could cause actual results to differ include, but are not limited to, the Company’s ability to complete its capacity building projects and annual preventative maintenance projects, continued variability in demand for and average selling price of disks, continued customer demand and the impact of demand variation on factory utilization, customers’ decisions to move to a mix-shift towards finished disks, the Company’s ability to achieve its operating yield, cost and profitability targets, the Company’s ability to satisfy customer qualification requirements and meet shipping demands, the Company’s ability to produce new generation disks in volume and the other factors described in the Company’s reports filed with the Securities and Exchange Commission, including, but not limited to, its most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q. Komag undertakes no obligation to update forward-looking statements to reflect events or circumstances occurring after the date of such statements.

KOMAG, INCORPORATED
Consolidated Income Statements
(in thousands, except per share data)
(Unaudited)

	Three Months			Three Months			Three Months
	Ended			Ended			Ended
	Apr 4, 2004			Dec 28, 2003			Mar 30, 2003
Net Sales	$	123,585		$	118,231		$	105,515
Cost of Sales		86,656			81,780			82,739
Gross Profit		36,929			36,451			22,776
Gross Profit      %		29.9	%		30.8	%		21.6	%
Research, Development, and Engineering Expense		11,622			10,996			9,909
Selling, General, and Administrative Expense		5,354			5,622			4,562
Gain on Disposal of Assets		(190	)		(1,151	)		(861	)
Operating Income		20,143			20,984			9,166
Interest Income		281			181			108
Interest Expense		(1,862	)		(3,058	)		(3,385	)
Other Income (Expense), Net		(50	)		(57	)		196
Income Before Income Taxes		18,512			18,050			6,085
Provision for Income Taxes		539			1,607			1,031
Net Income	$	17,973		$	6,443		$	5,054
Net Income %		14.5	%		13.9	%		4.8	%
Basic Net Income Per Share	$	0.68		$	0.70		$	0.22
Diluted Net Income Per Share	$	0.65		$	0.65		$	0.21
Basic Shares Outstanding		26,307			23,643			23,297
Diluted Shares Outstanding		27,662			25,150			23,934

NOTE: Certain reclassifications have been made to prior period balances in order to conform to the current period presentation.

KOMAG, INCORPORATED
Consolidated Balance Sheets
(in thousands)

	Apr 4, 2004			Dec 28, 2003
	(Unaudited)			(NOTE 1)
ASSETS
Cash and Cash Equivalents	$	80,858		$	70,058
Net Receivables		72,565			60,628
Inventories		38,644			25,501
Prepaid Expenses and Deposits		1,712			2,756
Total Current Assets		193,779			158,943
Property, Plant and Equipment, Net		198,582			184,536
Other Intangible Assets, Net		3,358			4,257
Other Assets		3,124			71
TOTAL ASSETS	$	398,843		$	347,807
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current Portion of Long-Term Debt	$	—		$	20,247
Trade Accounts Payable		48,964			40,117
Other Liabilities		16,934			25,054
Total Current Liabilities		65,898			85,418
Long-Term Debt		80,500			95,801
Common Stock		240,552			172,695
Deferred Stock-Based Compensation		(201	)		(228	)
Retained Earnings (Accumulated Deficit)		12,094			(5,879	)
TOTAL STOCKHOLDERS’ EQUITY		252,445			166,588
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$	398,843		$	347,807

NOTE 1: The Consolidated Balance Sheet at December 28, 2003 was derived from the audited financial statements.