
<PAGE>   1
                                  EXHIBIT 5(a)

                                November 8, 1996


Homeplex Mortgage Investments Corporation
5333 North 7th Street
Suite 219
Phoenix, AZ  85014

Gentlemen:

         We have acted as counsel to Homeplex Mortgage Investments Corporation,
a Maryland corporation (the "Company"), in connection with the registration
under the Securities Act of 1933, as amended, of 4,700,000 shares (the
"Shares") of the Company's common stock, par value $0.01 per share (the "Common
Stock"), as described in the Company's Registration Statement on Form S-4 (the
"Registration Statement") filed with the Securities and Exchange Commission.
The Company proposes to issue the Shares to the stockholders of Monterey Homes
Arizona II, Inc., an Arizona corporation, and Monterey Homes Construction,
Inc., an Arizona corporation (collectively, "Monterey"), in connection with the
acquisition of Monterey by the Company.

         In rendering this opinion, we have examined and relied upon executed
originals, counterparts or copies of such documents, records and certificates
(including certificates of public officials and officers of the Company) as we
considered necessary or appropriate for enabling us to express the opinions set
forth herein.  In all such examinations, we have assumed the authenticity and
completeness of all documents submitted to us as originals and the conformity
to originals and completeness of all documents submitted to us as photostatic,
conformed, notarized or certified copies.

         Based on the foregoing, we are of the opinion that the Shares, when
issued and sold to the Monterey stockholders as described in the Registration
Statement, will be validly issued, fully paid and nonassessable.

         This opinion may be filed as an exhibit to the Registration Statement.
We also consent to the reference to this firm as having passed on the validity
of the Common Stock under the caption "Legal Matters" in the Registration
Statement.  In giving this consent, we do not admit that we are included in 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 promulgated thereunder.

                                        Very truly yours,



                                        Hughes & Luce, L.L.P.





