EXHIBIT 8.1


                       [Letterhead of Goodwin Procter LLP]


                                 April 25, 2003



Inverness Medical Innovations, Inc.
51 Sawyer Road, Suite 200
Waltham, MA 02453

       Re:  Merger pursuant to Agreement and Plan of Merger by and among
            Inverness Medical Innovations, Inc., Geras Acquisition Corp. and
            Ostex International, Inc.

Ladies and Gentlemen:

This opinion is being delivered to you pursuant to Section 7.3(f) of the
Agreement and Plan of Merger dated as of September 6, 2002 and amended as of
February 18, 2003 (including exhibits and schedules thereto, the "MERGER
AGREEMENT"), by and among Inverness Medical Innovations, Inc, a Delaware
corporation ("PARENT"), Geras Acquisition Corp., a Washington corporation and
wholly owned subsidiary of Parent ("MERGERCO"), and Ostex International, Inc., a
Washington corporation ("COMPANY"). Pursuant to the Merger Agreement, MergerCo
shall merge with and into Company. We have acted as counsel to Parent in
connection with the Merger. This opinion relates to the qualification of the
Merger as a reorganization within the meaning of Section 368(a) of the Internal
Revenue Code of 1986, as amended (the "CODE").

For purposes of the opinion set forth below, we have reviewed and relied upon
Pre-Effective Amendment No. 1 to the Registration Statement on Form S-4 filed
with the United States Securities and Exchange Commission on April 25, 2003,
(the "Registration Statement"), the Merger Agreement and such other documents,
records and instruments as we have deemed necessary or appropriate as a basis
for our opinion. In addition, in rendering our opinion we have relied upon
certain statements, representations and warranties made by Parent, MergerCo and
Company set forth in representation letters provided to us by them in connection
with the preparation of this opinion (the "Tax Representation Letters"). We also
have assumed (without any independent investigation or review thereof) that:

       (a) Original documents submitted to us (including signatures thereto) are
authentic, documents submitted to us as copies conform to the original
documents, and all such documents have been (or will be by the Effective Time)
duly and validly executed and delivered where due execution and delivery are a
prerequisite to the effectiveness thereof;

       (b) All representations, warranties and statements made or agreed to by
Parent, MergerCo and Company, their managements, employees, officers, directors
and stockholders in connection with the Merger, including, but not limited to,
those set forth in the Registration Statement, the Merger Agreement and the Tax
Representation Letters are and will be true and




Inverness Medical Innovations, Inc.
April 25, 2003
Page 2


accurate at all relevant times, and no actions that are inconsistent with such
representations, warranties and statements will be taken;

       (c) All covenants contained in the Merger Agreement and the Tax
Representation Letters are and will be performed without waiver or breach of any
material provision thereof;

       (d) The Merger will be consummated in accordance with the Merger
Agreement without any waiver, breach or amendment of any material provision
thereof, and the Merger will be effective under applicable state law;

       (e) Each of Parent, MergerCo and Company will comply with all reporting
obligations with respect to the Merger required under the Code and the Income
Tax Regulations and Procedure and Administration Regulations thereunder (the
"Treasury Regulations"); and

       (f) Any representation, warranty or statement made "to the knowledge of"
or similarly qualified is and will be true, correct and complete as if made
without such qualification.

Any inaccuracy in, or breach of, any of the aforementioned representations,
warranties, statements and assumptions or any change after the date hereof in
applicable law could adversely affect our opinion.

Based upon and subject to the foregoing, as well as the limitations set forth
below, it is our opinion, under presently applicable federal income tax law,
that the Merger will qualify as a reorganization within the meaning of Section
368(a) of the Code.

Furthermore, based upon and subject to the limitations and qualifications set
forth herein, we are of the opinion that under current United States federal
income tax law, the discussion set forth in the Registration Statement under the
heading "Material Federal Income Tax Consequences," to the extent it describes
legal matters or legal conclusions, is accurate in all material respects.

                                      * * *

We express no opinion herein other than the opinion expressly set forth above.
In particular, this opinion does not address the tax consequences of any
transaction under any foreign, state, or local tax law and does not address the
federal tax consequences of any transaction other than the Merger as described
in the Merger Agreement. You should recognize that our opinion is not binding on
the Internal Revenue Service and that a court or the Internal Revenue Service
may disagree with the opinion contained herein. Although we believe that our
opinion will be sustained if challenged, there can be no assurance that this
will be the case. The discussion and conclusions set forth above are based upon
current provisions of the Code, the Treasury Regulations promulgated thereunder,
and existing administrative and judicial interpretations thereof, all of which
are subject to change, potentially with retroactive effect. Changes in
applicable law could adversely affect our opinion. We do not undertake to advise
you as to any changes after the date hereof in applicable law that may affect
our opinion.




Inverness Medical Innovations, Inc.
April 25, 2003
Page 3


This opinion is being delivered solely in connection with the filing of the
Registration Statement pursuant to the Merger Agreement and is intended for your
benefit. It may not be relied upon by, or made available to, any other person or
entity or used for any other purpose without our prior written consent.

We consent to the reference to our firm under the caption "Material Federal
Income Tax Consequences" in the Proxy Statement included in the Registration
Statement and to the reproduction and filing of this opinion as an exhibit to
the Registration Statement. In giving this consent, we do not thereby admit that
we are in the category of persons whose consent is required under Section 7 of
the Securities Act, nor do we admit that we are experts with respect to any part
of the Registration Statement within the meaning of the term "expert" as used in
the Securities Act.


                                         Very truly yours,



                                         /s/ Goodwin Procter LLP

                                         Goodwin Procter  LLP