[LETTERHEAD OF WILMER CUTLER PICKERING HALE AND DORR LLP]

October 25, 2004

Pioneer Fund
60 State Street
Boston, Massachusetts 02109

Ladies and Gentlemen:

Pioneer Fund (the "Fund") was established as a Delaware statutory trust under an
Agreement and Declaration of Trust dated April 26, 1996 (the "Declaration of
Trust"). The beneficial interests thereunder are represented by transferable
shares of beneficial interest, no par value.

The Trustees have the powers set forth in the Declaration of Trust, subject to
the terms, provisions and conditions therein provided. Pursuant to Article V,
Section 2 of the Declaration of Trust, the number of shares of beneficial
interest authorized to be issued under the Declaration of Trust is unlimited and
the Trustees are authorized to divide the shares into one or more series of
shares and one or more classes thereof as they deem necessary or desirable.
Pursuant to Article V, Sections 2 and 3 of the Declaration of Trust, the
Trustees are empowered in their discretion to issue shares of any series for
such amount and type of consideration, including cash or securities, and on such
terms as the Trustees may authorize, all without action or approval of the
shareholders. As of the date of this opinion, the Trustees have established one
additional class of shares of the Fund, designated as Investor Class shares.

We have examined the Declaration of Trust and By-Laws, each as amended from time
to time, of the Fund, and such other documents as we have deemed necessary or
appropriate for the purposes of this opinion, including, but not limited to,
originals, or copies certified or otherwise identified to our satisfaction, of
such documents, Fund records and other instruments. In our examination of the
above documents, we have assumed the genuineness of all signatures, the
authenticity of all documents submitted to us as originals and the conformity to
original documents of all documents submitted to us as certified of photostatic
copies.

Our opinions below are qualified to the extent that they may be subject to or
affected by (i) applicable bankruptcy, insolvency, reorganization, fraudulent
conveyance or transfer, moratorium or similar laws affecting the rights and
remedies of creditors generally, (ii) statutory or decisional law concerning
recourse by creditors to security in the absence of notice or hearing and (iii)
duties and standards imposed on creditors and parties to contracts, including,
without limitation, requirements of good faith, reasonableness and fair dealing.
Further, we do not express any opinion as to (i) the availability of the remedy
of specific performance or any other equitable remedy upon breach of any
provision of any agreement whether applied by a court of law or equity, (ii) the
successful assertion of any equitable defense, or (iii) the right of any party
to enforce the indemnification or contribution provisions of any agreement.



Pioneer Fund
October 25, 2004
Page 2

In rendering the opinion below, insofar as it relates to the good standing and
valid existence of the Fund, we have relied solely on a certificate of the
Secretary of the State of Delaware, dated as of a recent date, and such opinion
is limited accordingly and is rendered as of the date of such certificate.

This opinion is limited to the Delaware Statutory Trust Act statute, and we
express no opinion with respect to the laws of any other jurisdiction or to any
other laws of the State of Delaware. Further, we express no opinion as to
compliance with any state or federal securities laws, including the securities
laws of the State of Delaware.

Our opinion below, as it relates to the non-assessability of the shares of the
Fund, is qualified to the extent that any shareholder is, was or may become a
named Trustee of the Fund. It is also qualified to the extent that, pursuant to
Section 2 of Article VIII of the Declaration of Trust, the Trustees have the
power to cause shareholders, or shareholders of a particular series, to pay
certain custodian, transfer, servicing or similar agent charges by setting off
the same against declared but unpaid dividends or by reducing share ownership
(or by both means).

Subject to the foregoing, we are of the opinion that the Fund is a duly
organized and validly existing statutory trust in good standing under the laws
of the State of Delaware and that the Investor Class shares of the Fund, when
issued in accordance with the terms, conditions, requirements and procedures set
forth in the Declaration of Trust, the Fund's Registration Statements on Form
N-1A and this Form N-14, will be validly issued, fully paid and non-assessable
shares of beneficial interest in the Fund, subject to compliance with the
Securities Act of 1933, as amended (the "Securities Act"), the Investment
Company Act of 1940, as amended, and the applicable state laws regulating the
sale of securities.

Please note that we are opining only as to the matters expressly set forth
herein, and no opinion should be inferred as to any other matters. This opinion
is based upon currently existing statutes, rules, regulations and judicial
decisions, and we disclaim any obligation to advise you of any change in any of
these sources of law or subsequent legal or factual developments which might
affect any matters or opinions set forth herein.

We hereby consent to the filing of this opinion with the Securities and Exchange
Commission (the "Commission") as an exhibit to the Fund's Registration
Statements on Form N-1A and Form N-14. In giving such consent, we do not hereby
admit that we are in the category of persons whose consent is required under
Section 7 of the Securities Act or the rules and regulations of the Commission.

Very truly yours,


/S/ David C. Phelan

WILMER CUTLER PICKERING
HALE AND DORR LLP