EXHIBIT 5.1


                [VORYS, SATER, SEYMOUR AND PEASE LLP LETTERHEAD]


                                 March 22, 2006


Board of Directors
Peoples Bancorp Inc.
138 Putnam Street
Marietta, OH  45750

                  Re:      Peoples Bancorp Inc.
                           Post-Effective Amendment No. 3 to
                               Form S-3 Registration Statement
                           SEC Registration No. 33-54003

Gentlemen:

                  We have acted as counsel to Peoples Bancorp Inc., an Ohio
corporation (the "Company"), in connection with the Company's Post-Effective
Amendment No. 3 to Form S-3 Registration Statement ("Post-Effective Amendment
No. 3") pertaining to the Peoples Bancorp Inc. Dividend Reinvestment and Stock
Purchase Plan to be filed with the Securities and Exchange Commission (the
"SEC").

                  On June 7, 1994, the Company filed a Registration Statement on
Form S-3 (Registration No. 33-54003) (the "Registration Statement") with the SEC
in order to register 500,000 common shares, without par value (the "Common
Shares"), of the Company under the Securities Act of 1933, as amended (the
"Act"), for offering and sale to participants in the Peoples Bancorp Inc.
Dividend Reinvestment Plan. On April 23, 2003, the Company filed Post-Effective
Amendment No. 1 to the Registration Statement with the SEC in order to evidence
that the Company had determined that the Registration Statement was to cover
only the 500,000 Common Shares originally registered and not any additional
Common Shares resulting from any stock split or stock dividend occurring after
June 7, 1994 and prior to the completion of the offering of Common Shares of the
Company covered by the Registration Statement pursuant to the Dividend
Reinvestment Plan.

                  Effective November 28, 2005, the Company appointed a new
administrator for the Dividend Reinvestment Plan -- Shareowner Services, a
division of Wells Fargo Bank, N.A. Updated information concerning the operation
of the Dividend Reinvestment Plan and the new administrator of the Dividend
Reinvestment Plan was included in the prospectus filed as part of Post-Effective
Amendment No. 2 to the Registration Statement, which Post-Effective Amendment
No. 2 was filed with the SEC on December 13, 2005.

                  Effective March 9, 2006, the Company amended the Dividend
Reinvestment Plan to allow participants to purchase Common Shares of the Company
by making optional cash investments upon specified terms. In order to reflect
the addition of this optional cash investment feature, the Company modified the
name of the Dividend Reinvestment Plan to be the Peoples Bancorp Inc. Dividend
Reinvestment and Stock Purchase Plan. Information concerning the operation of
the Dividend Reinvestment and Stock Purchase Plan (the "Plan") with the optional
cash investment feature is provided in the prospectus filed as part of
Post-Effective Amendment No. 3.

                  The Company has advised us that, as of the date hereof,
286,053 Common Shares of the Company remained available for issuance pursuant to
the Plan.

                  In connection with rendering this opinion, we have examined,
to the extent deemed necessary, originals or copies, the authenticity of which
has been established to our satisfaction, of: (i) the Registration Statement and
Post-Effective Amendments No. 1 and 2 thereto; (ii) Post-Effective Amendment No.
3; (iii) the Amended Articles of Incorporation of the Company, as currently in
effect; (iv) the Code of Regulations of the Company, as currently in effect; and
(v) certain resolutions adopted by the Board of Directors of the Company. We
have also relied upon such representations of the officers of the Company and
examined such records and authorities of law as we have deemed relevant as a
basis for this opinion.

                  In our examinations of the aforesaid documents and records, we
have assumed, without independent investigation or examination, the authenticity
of all documents and records examined by us, the genuineness of all signatures,
the legal capacity of all individuals who have executed any of the aforesaid
documents, the authority of all individuals entering and maintaining records,
and the conformity to authentic originals of all items submitted to us as copies
(whether certified, conformed, photostatic or by other electronic means) of
documents or records.

                  We have relied solely upon the examinations and inquiries
recited herein and, except for the examinations and inquiries recited herein, we
have not undertaken any independent investigation to determine the existence or
absence of any facts, and no inference as to our knowledge concerning such facts
should be drawn.

                  Based upon and subject to the foregoing, and the further
qualifications and limitations set forth below, as of the date hereof, we are of
the opinion that the Common Shares of the Company issuable under the Plan, when
issued and sold in accordance with the terms and provisions of the Plan and the
Registration Statement, as amended, will be validly issued, fully-paid and
non-assessable.

                  Members of our firm are admitted to the Bar of the State of
Ohio and we express no opinion as to the laws of any jurisdiction other than the
laws of the State of Ohio, including the applicable provisions of the Ohio
Constitution and the reported judicial decisions interpreting those laws, and
the laws of the United States of America.

                  This opinion is based upon the laws and legal interpretations
in effect, and the facts and circumstances existing, on the date hereof, and we
assume no legal obligation to revise or supplement this opinion should any such
law or legal interpretation be changed by legislative action, judicial
interpretation or otherwise or should there be any change in such facts and
circumstances.

                  Our opinion is expressly limited to the matters set forth
above, and we render no opinion, whether by implication or otherwise, as to any
other matters relating to the Company, the Plan, or the Common Shares issuable
under the Plan.

                  We consent to the filing of this opinion as an exhibit to the
Company's Registration Statement, as amended by Post-Effective Amendment No. 3,
and to the reference to our firm under the caption "Legal Matters" in the
prospectus relating to the Plan, filed as part of the Registration Statement, as
amended by Post-Effective Amendment No. 3, filed by the Company with the SEC, as
well as any amendments or supplements thereto. In giving this consent, however,
we do not thereby admit that we fall within the category of persons whose
consent is required under Section 7 or Section 11 of the Act or the rules and
regulations of the SEC promulgated thereunder.

                                  Very truly yours,

                              /s/ Vorys, Sater, Seymour and Pease LLP

                                  VORYS, SATER, SEYMOUR AND PEASE LLP