EXHIBIT 5.1

 
               [LETTERHEAD OF BALLARD SPAHR ANDREWS & INGERSOLL]


                               December 10, 1997

Health Care Property Investors, Inc.
10990 Wilshire Boulevard
Suite 1200
Los Angeles,  California  90024


     Re:   Health Care Property Investors, Inc., a Maryland corporation (the
           "Company") - up to One Million Four Hundred Thirty-Seven Thousand
           Five Hundred (1,437,500) shares (the "Shares") of the Common Stock of
           the Company, par value $1.00 per share (the "Common Stock"), to be
           issued and sold pursuant to Registration Statement on Form S-3, as
           amended (Registration No. 333-29485), including the Prospectus dated
           September 19, 1997, comprising a part thereof (the "Prospectus"), and
           the Prospectus Supplement, dated December 10, 1997 (the "Prospectus
           Supplement")
           ---------------------------------------------------------------------

Ladies and Gentlemen:

    In connection with the registration of the offering and sale of the Shares 
under the Securities Act of 1933, as amended (the "Act"), by the Company on 
Form S-3 filed with the Securities and Exchange Commission on or about June 18, 
1997, as amended, (the "Registration Statement"), you have requested our opinion
with respect to the matters set forth below.

    We have acted as special Maryland corporate counsel for the Company in 
connection with the matters described herein.  In our capacity as special 
Maryland corporate counsel to the Company, we have reviewed and are familiar 
with proceedings proposed to be taken by the Company in connection with the 
authorization, issuance and sale of the Shares, and for purposes of this opinion
have assumed such proceedings will be timely completed in the manner presently 
proposed. In addition, we have relied upon certificates and advice from the 
officers of the Company upon which we believe we are justified in relying and on
various certificates from, and documents recorded with, the State Department of
Assessments and Taxation of Maryland (the "SDAT"), including the charter of the
Company (the "Charter"), consisting of Articles of Restatement



 
BALLARD SPAHR ANDREWS & INGERSOLL


Health Care Properties Investors, Inc.
December 10, 1997
Page 2



filed with the SDAT on April 27, 1992 and Articles Supplementary filed with the
SDAT on or about September 26, 1997. We have also examined the Bylaws of the
Company, as amended through the date hereof (the "Bylaws"), and Resolutions of
the Board of Directors of the Company and committees thereof adopted on or
before the date hereof and in full force and effect on the date hereof; and such
laws, records, documents, certificates, opinions and instruments as we deem
necessary to render this opinion.


     We have assumed the genuineness of all signatures, the authenticity of all
documents submitted to us as originals and the conformity to the originals of
all documents submitted to us as certified, photostatic or conformed copies. In
addition, we have assumed that each person executing any instrument, document or
certificate referred to herein on behalf of any party is duly authorized to do
so. We have also assumed that none of the Shares will be issued or transferred
in violation of the restrictions on ownership and transfer of stock contained in
the Charter of the Company and described in the Prospectus under the caption
"Transfer Restrictions, Redemption and Business Combination Provisions."

     Based on the foregoing, and subject to the assumptions and qualifications
set forth herein, it is our opinion that, as of the date of this letter, the
Shares have been duly authorized by all necessary corporate action on the part
of the Company, and the Shares will, upon issuance and delivery in accordance
with the terms and conditions described in the Registration Statement against
payment of the purchase price therefor as determined by the Board of Directors
of the Company or a committee thereof, be validly issued, fully paid and
nonassessable.

     We consent to your filing this opinion as an exhibit to the Registration
Statement, and further consent to the filing of this opinion as an exhibit to
the applications to securities commissioners for the various states of the
United States for registration of the Shares. We also consent to the
identification of our firm as Maryland counsel to the Company in the section of
the Prospectus (which is part of the Registration Statement) entitled "Legal
Matters."

     The opinions expressed herein are limited to the laws of the state of
Maryland and we express no opinion concerning any laws other than the laws of
the State of Maryland. Furthermore, the opinions presented in this letter are
limited to the matters

 
BALLARD SPAHR ANDREWS  & INGERSOLL

Health Care Properties Investors, Inc.
December 10, 1997
Page 3


specifically set forth herein and no other opinion shall be inferred beyond the 
matters expressly stated.

                                           Very truly yours,


                                           Ballard Spahr Andrews & Ingersoll