HALE AND DORR LLP
                               Counsellors At Law


                                www.haledorr.com
                       60 STATE STREET o BOSTON, MA 02109
                         617-526-6000 o FAX 617-526-5000


                                                          _____________, 2002


John Hancock Investment Trust III, on behalf of
John Hancock International Fund
101 Huntington Avenue
Boston, MA 02199

John Hancock Institutional Series Trust, on behalf of
John Hancock International Equity Fund
101 Huntington Avenue
Boston, MA 02199

Ladies and Gentlemen:

      This opinion is being delivered to you in connection with the Agreement
and Plan of Reorganization (the "Agreement") made as of ___________, 2002
between John Hancock Investment Trust III, on behalf of John Hancock
International Fund ("Acquiring Fund"), and John Hancock Institutional Series
Trust on behalf of John Hancock International Equity Fund ("Acquired Fund").
Pursuant to the Agreement, Acquiring Fund will acquire all of the assets of
Acquired Fund in exchange solely for (i) the assumption by Acquiring Fund of all
of the liabilities of Acquired Fund (the "Acquired Fund Liabilities") and (ii)
the issuance of shares of beneficial interest of Acquiring Fund (the "Acquiring
Fund Shares") to Acquired Fund, followed by the distribution by Acquired Fund,
in liquidation of Acquired Fund, of the Acquiring Fund Shares to the
shareholders of Acquired Fund and the termination of Acquired Fund (the
foregoing together constituting the "Transaction"). All section references,
unless otherwise indicated, are to the United States Internal Revenue Code of
1986, as amended (the "Code").

      In rendering this opinion, we have examined and relied upon (i) the
prospectus for Acquiring Fund, dated___________; (ii) the statement of
additional information for Acquiring Fund, dated________; (iii) the prospectus
for Acquired Fund, dated__________; (iv) the statement of additional information
for Acquired Fund, dated__________; (v) the Notice of Meeting of Shareholders
Scheduled for ___________and the accompanying proxy statement and prospectus on
Form N-14 (the "Proxy Statement"); (vi) the Agreement; (vii) the tax
representation certificates attached to the Agreement and relevant to this
opinion (the "Representation Certificates"); and (viii) such other documents as
we deemed necessary or relevant to our analysis.

      In our examination of documents, we have assumed the authenticity of
original documents, the accuracy of copies, the genuineness of signatures, and
the legal capacity of signatories. We have assumed that all parties to the
Agreement and to any other documents examined by us have acted, and will act, in
accordance with the terms of such Agreement and documents and that the
Transaction will be consummated pursuant to the terms and conditions set forth
in the Agreement without the waiver or modification of any such terms and
conditions. Furthermore, we have assumed that all representations contained in
the Agreement, as well as those representations contained in the Representation

- --------------------------------------------------------------------------------

BOSTON         WASHINGTON, DC        NEW YORK          RESTON            LONDON*
- --------------------------------------------------------------------------------
Hale and Dorr LLP Includes Professional Corporations  *an independent joint
venture law firm



John Hancock Investment Trust III, et al.
______________, 2002
Page 2


Certificates are, on the date hereof, and will be, at the consummation of the
Transaction, true and complete in all material respects, and that any
representation made in any of the documents referred to herein "to the knowledge
and belief" (or similar qualification) of any person or party is, and at the
consummation of the Transaction will be, correct without such qualification. We
have also assumed that as to all matters for which a person or entity has
represented that such person is not a party to, does not have, or is not aware
of any plan, intention, understanding or agreement, there is no such plan,
intention, understanding or agreement. We have not attempted to verify
independently such representations.

      The conclusions expressed herein represent our judgment regarding the
proper treatment of the Transaction under the income tax laws of the United
States based upon the Code, case law, Treasury Regulations, and the rulings and
other pronouncements of the Internal Revenue Service (the "Service") in effect
on the date of this opinion. No assurances can be given that such laws will not
be amended or otherwise changed after the consummation of the Transaction or
that such changes will not affect the conclusions expressed herein.
Nevertheless, we undertake no responsibility to advise you of any developments
after the consummation of the Transaction in the application or interpretation
of the income tax laws of the United States.

      Our opinion represents our best judgment regarding how a court would
decide if presented with the issues addressed herein and is not binding upon the
Service or any court. Moreover, our opinion does not provide any assurance that
a position taken in reliance on such opinion will not be challenged by the
Service and does not constitute any representation or warranty that such
position, if so challenged, will not be rejected by a court.

      This opinion addresses only the specific United States federal income tax
consequences of the Transaction set forth below, and does not address any other
federal, state, local, or foreign income, estate, gift, transfer, sales, or
other tax consequences that may result from the Transaction or any other action
(including any action taken in connection with the Transaction).

      On the basis of and subject to the foregoing and in reliance upon the
representations, facts and assumptions described above, we are of the opinion
that the acquisition by Acquiring Fund of all of the assets of Acquired Fund
solely in exchange for the issuance of Acquiring Fund Shares to Acquired Fund
and the assumption of the Acquired Fund Liabilities by Acquiring Fund, followed
by the distribution by Acquired Fund, in liquidation of Acquired Fund, of
Acquiring Fund Shares to Acquired Fund shareholders in exchange for their
Acquired Fund Shares and the termination of Acquired Fund, will constitute a
"reorganization" within the meaning of Section 368(a) of the Code.

      No opinion is expressed or implied regarding the tax consequences of any
other aspects of the Transaction, including but not limited to its effect, if
any, on the availability of, or limitations on, any capital loss carryforwards
of Acquired Fund, and the payment of any Acquired Fund or Acquiring Fund
expenses by John Hancock Advisers, LLC, except as expressly set forth above.





John Hancock Investment Trust III, et al.
______________, 2002
Page 3


      This opinion is being delivered to you solely in connection with the
closing condition set forth in Section 8.6 of the Agreement. It may not be
relied upon for any other purpose or by any other person or entity, and may not
be made available to any other person or entity without our prior written
consent.


                                             Very truly yours,



                                             /s/HALE AND DORR LLP
                                             --------------------





                               HALE AND DORR LLP
                               Counsellors At Law



                                www.haledorr.com
                       60 STATE STREET o BOSTON, MA 02109
                         617-526-6000 o FAX 617-526-5000


                                                          _____________, 2002


John Hancock Investment Trust III, on behalf of
John Hancock Mid Cap Growth Fund
101 Huntington Avenue
Boston, MA 02199

John Hancock Institutional Series Trust, on behalf of
John Hancock Medium Capitalization Growth Fund
101 Huntington Avenue
Boston, MA 02199

Ladies and Gentlemen:

      This opinion is being delivered to you in connection with the Agreement
and Plan of Reorganization (the "Agreement") made as of ___________, 2002
between John Hancock Investment Trust III on behalf of John Hancock Mid Cap
Growth Fund ("Acquiring Fund"), and John Hancock Institutional Series Trust on
behalf of John Hancock Medium Capitalization Growth Fund ("Acquired Fund").
Pursuant to the Agreement, Acquiring Fund will acquire all of the assets of
Acquired Fund in exchange solely for (i) the assumption by Acquiring Fund of all
of the liabilities of Acquired Fund (the "Acquired Fund Liabilities") and (ii)
the issuance of shares of beneficial interest of Acquiring Fund (the "Acquiring
Fund Shares") to Acquired Fund, followed by the distribution by Acquired Fund,
in liquidation of Acquired Fund, of the Acquiring Fund Shares to the
shareholders of Acquired Fund and the termination of Acquired Fund (the
foregoing together constituting the "Transaction"). All section references,
unless otherwise indicated, are to the United States Internal Revenue Code of
1986, as amended (the "Code").

      In rendering this opinion, we have examined and relied upon (i) the
prospectus for Acquiring Fund, dated___________; (ii) the statement of
additional information for Acquiring Fund, dated________; (iii) the prospectus
for Acquired Fund, dated__________; (iv) the statement of additional information
for Acquired Fund, dated__________; (v) the Notice of Meeting of Shareholders
Scheduled for ___________and the accompanying proxy statement and prospectus on
Form N-14 (the "Proxy Statement"); (vi) the Agreement; (vii) the tax
representation certificates attached to the Agreement and relevant to this
opinion (the "Representation Certificates"); and (viii) such other documents as
we deemed necessary or relevant to our analysis.

      In our examination of documents, we have assumed the authenticity of
original documents, the accuracy of copies, the genuineness of signatures, and
the legal capacity of signatories. We have assumed that all parties to the
Agreement and to any other documents examined by us have acted, and will act, in
accordance with the terms of such Agreement and documents and that the
Transaction will be consummated pursuant to the terms and conditions set forth
in the Agreement without the waiver or modification of any such terms and
conditions. Furthermore, we have assumed that all representations contained in
the Agreement, as well as those representations contained in the Representation

- --------------------------------------------------------------------------------

BOSTON         WASHINGTON, DC         NEW YORK          RESTON           LONDON*
- --------------------------------------------------------------------------------
Hale and Dorr LLP Includes Professional Corporations  *an independent joint
venture law firm



John Hancock Investment Trust III, et al.
______________, 2002
Page 2


Certificates are, on the date hereof, and will be, at the consummation of the
Transaction, true and complete in all material respects, and that any
representation made in any of the documents referred to herein "to the knowledge
and belief" (or similar qualification) of any person or party is, and at the
consummation of the Transaction will be, correct without such qualification. We
have also assumed that as to all matters for which a person or entity has
represented that such person is not a party to, does not have, or is not aware
of any plan, intention, understanding or agreement, there is no such plan,
intention, understanding or agreement. We have not attempted to verify
independently such representations.

      The conclusions expressed herein represent our judgment regarding the
proper treatment of the Transaction under the income tax laws of the United
States based upon the Code, case law, Treasury Regulations, and the rulings and
other pronouncements of the Internal Revenue Service (the "Service") in effect
on the date of this opinion. No assurances can be given that such laws will not
be amended or otherwise changed after the consummation of the Transaction or
that such changes will not affect the conclusions expressed herein.
Nevertheless, we undertake no responsibility to advise you of any developments
after the consummation of the Transaction in the application or interpretation
of the income tax laws of the United States.

      Our opinion represents our best judgment regarding how a court would
decide if presented with the issues addressed herein and is not binding upon the
Service or any court. Moreover, our opinion does not provide any assurance that
a position taken in reliance on such opinion will not be challenged by the
Service and does not constitute any representation or warranty that such
position, if so challenged, will not be rejected by a court.

      This opinion addresses only the specific United States federal income tax
consequences of the Transaction set forth below, and does not address any other
federal, state, local, or foreign income, estate, gift, transfer, sales, or
other tax consequences that may result from the Transaction or any other action
(including any action taken in connection with the Transaction).

      On the basis of and subject to the foregoing and in reliance upon the
representations, facts and assumptions described above, we are of the opinion
that the acquisition by Acquiring Fund of all of the assets of Acquired Fund
solely in exchange for the issuance of Acquiring Fund Shares to Acquired Fund
and the assumption of the Acquired Fund Liabilities by Acquiring Fund, followed
by the distribution by Acquired Fund, in liquidation of Acquired Fund, of
Acquiring Fund Shares to Acquired Fund shareholders in exchange for their
Acquired Fund Shares and the termination of Acquired Fund, will constitute a
"reorganization" within the meaning of Section 368(a) of the Code.

      No opinion is expressed or implied regarding the tax consequences of any
other aspects of the Transaction, including but not limited to its effect, if
any, on the availability of, or limitations on, any capital loss carryforwards
of Acquired Fund, and the payment of any Acquired Fund or Acquiring Fund
expenses by John Hancock Advisers, LLC, except as expressly set forth above.



John Hancock Investment Trust III, et al.
______________, 2002
Page 3



      This opinion is being delivered to you solely in connection with the
closing condition set forth in Section 8.6 of the Agreement. It may not be
relied upon for any other purpose or by any other person or entity, and may not
be made available to any other person or entity without our prior written
consent.


                                            Very truly yours,



                                            /s/HALE AND DORR LLP
                                            --------------------