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                                                                     EXHIBIT 5.1

July 24, 1997



Pioneer Americas Acquisition Corp.
4200 NationsBank Center
700 Louisiana Street
Houston, Texas 77002

Re:     Registration Statement on Form S-4
        (File No. 333-30683)

Dear Sirs:

We are counsel to Pioneer Americas Acquisition Corp., a Delaware corporation
(the "Company"), and its subsidiaries (the "Subsidiary Guarantors" and together
with the Company, the "Issuers"), and have acted as such in connection with
various legal matters relating to the filing of a Registration Statement on
Form S-4 (File No. 333-30683) (the "Registration Statement") under the
Securities Act of 1933, as amended (the "Securities Act"), covering up to
$200,000,000 in aggregate principal amount of 9-1/4% Series B Senior Secured
Notes due 2007 (the "Exchange Notes") offered in exchange for up to
$200,000,000 in aggregate principal amount of outstanding 9-1/4% Series A
Senior Secured Notes due 2007 originally issued and sold in reliance upon an
exemption from registration under the Securities Act (the "Original Notes").
The Original Notes were issued under, and the Exchange Notes are to be issued
under, the Indenture, dated as of June 17, 1997 (the "Indenture"), among the
Issuers and the United States Trust Company of New York, as trustee. The
exchange will be made pursuant to an exchange offer (the "Exchange Offer")
contemplated by the Registration Statement. Capitalized terms used but not
otherwise defined herein shall have the meanings assigned to them in the
Registration Statement.

In so acting, we have examined copies of such records of the Issuers and such
other certificates and documents as we have deemed relevant and necessary for
the opinions hereinafter set forth. In such examination, we have assumed the
genuineness of all signatures, the authenticity of all documents submitted
to us as originals and the conformity to authentic originals of all documents
submitted to us as certified or reproduced copies. We have also assumed the
legal capacity of all persons executing such documents and the truth and
correctness of any representations or warranties therein contained. As to
various questions of fact material to such opinions, we have relied upon
certificates of officers of the Issuers and of public officials.

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Pioneer Americas Acquisition Corp.
July 24, 1997
Page 2

Based upon the foregoing, we are of the opinion that:

1.  The Company, Pioneer Americas, Inc., Pioneer Chlor Alkali Company, Inc.
    and Pioneer (East), Inc. are duly formed and validly existing under the 
    laws of the State of Delaware.

2.  The execution and delivery of the Indenture has been duly authorized by the
    Issuers, and the Indenture constitutes a legal, valid and binding obligation
    of the Issuers, enforceable against the Issuers in accordance with the terms
    thereof, except as enforcement thereof may be limited by bankruptcy,
    insolvency, reorganization, fraudulent conveyance and other similar laws
    affecting the enforcement thereof is subject to general principles of equity
    (regardless of whether enforcement is considered in a proceeding in equity
    or at law).

3.  The Exchange Notes have been duly authorized and, when duly executed by the
    proper officers of the Company, duly authenticated by the Trustee and issued
    by the Company in accordance with the terms of the Indenture and the
    Exchange Offer, will constitute legal, valid and binding obligations of the
    Company, will be entitled to the benefits of the Indenture and will be
    enforceable against the Company in accordance with their terms, except as
    enforcement thereof may be limited by bankruptcy, insolvency, 
    reorganization, fraudulent conveyance and other similar laws affecting the 
    enforcement of creditors' rights generally and except as enforcement 
    thereof is subject to general principles of equity (regardless of whether 
    enforcement is considered in a proceeding in equity or at law).

4.  The Guarantee have been duly authorized and, when the Exchange Notes have
    been duly executed and authenticated, and the Guarantees have been duly
    executed, in accordance with the terms of the Indenture, and the Exchange
    Notes have been delivered to the holders as described in the Prospectus, the
    Guarantees will constitute legal, valid and binding obligations of the
    Subsidiary Guarantors, will be entitled to the benefits of the Indenture
    and will be enforceable against the Subsidiary Guarantors in accordance with
    their term, except as enforcement thereof may be limited by bankruptcy,
    insolvency, reorganization, fraudulent conveyance and other similar laws
    affecting the enforcement of creditors' rights generally and except as
    enforcement thereof is subject to general principles of equity (regardless
    of whether enforcement is considered in a proceeding in equity or at law).

This opinion is limited to the laws of the State of New York, the General
Corporation Law of the State of Delaware and the federal
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Pioneer Americas Acquisition Corp.
July 24, 1997
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laws of the United States of the type typically applicable to transactions
contemplated by the Exchange Offer, and we do not express any opinion with
respect to the laws of any other country, state or jurisdiction.  In rendering
our opinions expressed in paragraphs 2, 3 and 4 above, we have relied on the
opinion of Kent R. Stephenson, Esq., Vice President, General Counsel and
Secretary of the Company, addressed to you and of even date herewith, to the
extent our opinions relate to due authorization, execution and delivery of
Subsidiary Guarantors not incorporated in the State of Delaware.

This opinion letter is limited to the matters stated herein and no opinion is
implied or may be inferred beyond the matters expressly stated.

This letter speaks only as of the date hereof and is limited to present
statutes, regulations and administrative and judicial interpretations.  We
undertake no responsibility to update or supplement this letter after the date
hereof.

We consent to being named in the Registration Statement and related Prospectus
as counsel who are passing upon the legality of the Exchange Notes for the
Company and the Guarantees for the Subsidiary Guarantors and to the reference
to our name under the caption "Legal Matters" in such Prospectus.  We also
consent to your filing copies of this opinion as an exhibit to the Registration
Statement or any amendment thereto.

Very truly yours,

/s/ Willkie Farr & Gallagher