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                                                                     Exhibit 5.1




                 [LETTERHEAD OF RICHARDS, LAYTON & FINGER, P.A.]





                                  August 1, 2001





Fresenius Medical Care AG
Else-Kroner Str. 1
61346 Bad Homurg v.d.H.
Germany

FMC Trust Finance S.a.r.l. Luxembourg-III
7A rue Stumper
L-2557 Luxembourg

         Re:      Fresenius Medical Care Capital Trust IV and Fresenius Medical
                  Care Capital Trust V

Ladies and Gentlemen:

                  We have acted as special Delaware counsel for Fresenius
Medical Care AG, a corporation organized and existing under the laws of Germany
(the "Company"), Fresenius Medical Care Capital Trust IV, a Delaware business
trust ("Trust IV") and Fresenius Medical Care Capital Trust V, a Delaware
business trust ("Trust V") (Trust IV and Trust V are hereinafter collectively
referred to as the "Trusts" and sometimes hereinafter individually referred to
as a "Trust"), in connection with the matters set forth herein. At your request,
this opinion is being furnished to you.

                  For purposes of giving the opinions hereinafter set forth, our
examination of documents has been limited to the examination of originals or
copies of the following:

                  (a)   The Certificate of Trust of Trust IV (the "Certificate
                        of Trust"), as filed with the office of the Secretary of
                        State of the State of Delaware (the "Secretary of
                        State") on February 12, 1998;

                  (b)   the Certificate of Trust of Trust V, as filed with the
                        office of the Secretary of State on June 1, 2001;

                  (c)   the Declaration of Trust of Trust IV, dated as of
                        February 12, 1998;

                  (d)   the First Amendment to the Declaration of Trust of Trust
                        IV, dated as of June 5, 2001;

                  (e)   the Amended and Restated Declaration of Trust of Trust
                        IV, dated as of June 6, 2001;

                  (f)   the Declaration of Trust of Trust V, dated as of June 1,
                        2001;


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FMC Trust Finance S.a.r.l. Luxembourg-III
August 1, 2001
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                  (g)   the Amended and Restated Declaration of Trust of Trust
                        V, dated as of June 15, 2001 (the documents listed in
                        (c) through (g) above are collectively referred to
                        herein as the "Trust Agreements");

                  (h)   the Registration Statement (the "Registration
                        Statement") on Form F-4, including a preliminary
                        prospectus with respect to the Trusts, filed by the
                        Company with the Securities and Exchange Commission on
                        or about the date of this opinion (the "Prospectus"),
                        relating to the Preferred Securities of the Trusts
                        representing preferred undivided beneficial interests in
                        the assets of the Trusts (each, a Preferred Security"
                        and collectively, the "Preferred Securities" to be
                        issued in exchange for certain outstanding preferred
                        securities of the Trusts); and

                  (i)   a Certificate of Good Standing for each of the Trusts,
                        dated August 1, 2001, obtained from the Secretary of
                        State.

                  Initially capitalized terms used herein and not otherwise
defined are used as defined in the Trust Agreements.

                  For purposes of this opinion, we have not reviewed any
documents other than the documents listed in paragraphs (a) through (i) above.
In particular, we have not reviewed any document (other than the documents
listed in paragraphs (a) through (i) above) that is referred to in or
incorporated by reference into the documents reviewed by us. We have assumed
that there exists no provision in any document that we have not reviewed that is
inconsistent with the opinions stated herein. We have conducted no independent
factual investigation of our own but rather have relied solely upon the
foregoing documents, the statements and information set forth therein and the
additional matters recited or assumed herein, all of which we have assumed to be
true, complete and accurate in all material respects.

                  With respect to all documents examined by us, we have assumed
(i) the authenticity of all documents submitted to us as authentic originals,
(ii) the conformity with the originals of all documents submitted to us as
copies or forms, and (iii) the genuineness of all signatures.

                  For purposes of this opinion, we have assumed (i) that each of
the Trust Agreements will constitute the entire agreement among the parties
thereto with respect to the subject matter thereof, including with respect to
the creation, operation and termination of the applicable Trust, and that the
Trust Agreements and the Certificates of Trust will be in full force and effect
and will not be amended, (ii) except to the extent provided in paragraph 1
below, the due organization or due formation, as the case may be, and valid
existence in good standing of each party to the documents examined by us under
the laws of the jurisdiction governing its organization or formation, (iii) the
legal capacity of natural persons who are parties to the documents examined by
us, (iv) that each of the parties to the documents examined by us has the power
and authority to execute and deliver, and to perform its obligations under, such
documents, (v) the due authorization, execution and delivery by all parties
thereto of all documents examined by us, (vi) the receipt by each Person to whom
a Preferred Security is to be issued by the Trusts (collectively, the "Preferred
Security Holders") of a Preferred Security Certificate for such Preferred
Security and the payment for such Preferred Security, in accordance with the
Trust Agreements and the Registration Statement, and (vii) that the Preferred
Securities are authenticated, issued and sold to the Security Holders in
accordance with the Trust Agreements and the Registration Statement. We have not
participated in the preparation of the Registration Statement or the Prospectus
and assume no responsibility for their contents.

                  This opinion is limited to the laws of the State of Delaware
(excluding the securities laws of the State of Delaware), and we have not
considered and express no opinion on the laws of any other
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August 1, 2001
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jurisdiction, including federal laws and rules and regulations relating thereto.
Our opinions are rendered only with respect to Delaware laws and rules,
regulations and orders thereunder which are currently in effect.

                  Based upon the foregoing, and upon our examination of such
questions of law and statutes of the State of Delaware as we have considered
necessary or appropriate, and subject to the assumptions, qualifications,
limitations and exceptions set forth herein, we are of the opinion that:

                  1. Each of the Trusts has been duly created and is validly
existing in good standing as a business trust under the Business Trust Act.

                  2. The Preferred Securities of each Trust will represent valid
and, subject to the qualifications set forth in paragraph 3 below, legally
issued, fully paid and nonassessable undivided beneficial interests in the
assets of the applicable Trust.

                  3. The Preferred Security Holders, as beneficial owners of the
applicable Trust, will be entitled to the same limitation of personal liability
extended to stockholders of private corporations for profit organized under the
General Corporation Law of the State of Delaware. We note that the Preferred
Security Holders may be obligated to make payments as set forth in the Trust
Agreement.

                  We consent to the filing of this opinion with the Securities
and Exchange Commission as an exhibit to the Registration Statement. We hereby
consent to the use of our name under the heading "Legal Opinions" in the
Prospectus. In giving the foregoing consents, we do not thereby admit that we
come within the category of persons whose consent is required under Section 7 of
the Securities Act of 1933, as amended, or the rules and regulations of the
Securities and Exchange Commission thereunder. Except as stated above, without
our prior written consent, this opinion may not be furnished or quoted to, or
relied upon by, any other person for any purpose.

                                             Very truly yours,

                                             /s/ Richards, Layton & Finger, P.A.


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