ACTIVE ASSETS INSTITUTIONAL GOVERNMENT SECURITIES TRUST

                           SELECTED DEALERS AGREEMENT

Gentlemen:

    Morgan Stanley Distributors Inc. (the "Distributor") has a distribution
agreement (the "Distribution Agreement") with Active Assets Institutional
Government Securities Trust, a Massachusetts business trust (the "Fund"),
pursuant to which it acts as the Distributor for the sale of the Fund's shares
of common stock, par value $0.01 per share (the "Shares"). Under the
Distribution Agreement, the Distributor has the right to distribute Shares for
resale.

    The Fund is an open-end management investment company registered under the
Investment Company Act of 1940, as amended, and the Shares being offered to the
public are registered under the Securities Act of 1933, as amended. You have
received a copy of the Distribution Agreement between us and the Fund and
reference is made herein to certain provisions of such Distribution Agreement.
The terms used herein, including "Prospectus" and "Registration Statement" of
the Fund and "Selected Dealer" shall have the same meaning in this Agreement as
in the Distribution Agreement. As principal, we offer to sell shares to you, as
a Selected Dealer, upon the following terms and conditions:

    1.  In all sales of Shares to the public you shall act as dealer for your
own account, and in no transaction shall you have any authority to act as agent
for the Fund, for us or for any Selected Dealer.

    2.  Orders received from you will be accepted through us or on our behalf
only at the net asset value applicable to each order, as set forth in the
current Prospectus. The procedure relating to the handling of orders shall be
subject to instructions which we or the Fund shall forward from time to time to
you. All orders are subject to acceptance or rejection by the Distributor or the
Fund in the sole discretion of either.

    3.  You shall not place orders for any Shares unless you have already
received purchase orders for such Shares at the applicable net asset values and
subject to the terms hereof and of the Distribution Agreement and the
Prospectus. You agree that you will not offer or sell any of the Shares except
under circumstances that will result in compliance with the applicable Federal
and state securities laws and that in connection with sales and offers to sell
Shares you will furnish to each person to whom any such sale or offer is made a
copy of the Prospectus (as then amended or supplemented) and will not furnish to
any person any information relating to the Shares, which is inconsistent in any
respect with the information contained in the Prospectus (as then amended or
supplemented) or cause any advertisement to be published by radio or television
or in any newspaper or posted in any public place or use any sales promotional
material without our consent and the consent of the Fund.

    4.  The Distributor will compensate you for sales of shares of the Fund and
personal services to Fund shareholders by paying you a sales charge and/or other
commissions, which may be in the form of a gross sales credit and/or an annual
residual commission) and/or a service fee, under the terms and in the percentage
amounts as may be in effect from time to time by the Distributor.

    5.  You shall not withhold placing orders received from your customers so as
to profit yourself as a result of such withholding; e.g., by a change in the
"net asset value" from that used in determining the offering price to your
customers.

    6.  If any Shares sold to you under the terms of this Agreement are
repurchased by us for the account of the Fund or are tendered for redemption
within seven business days after the date of the confirmation of the original
purchase by you, it is agreed that you shall forfeit your right to, and refund
to us, any commission received by you with respect to such Shares.

    7.  No person is authorized to make any representations concerning the
Shares or the Fund except those contained in the current Prospectus and in such
printed information subsequently issued by us or the Fund as information
supplemental to such Prospectus. In purchasing Shares through us you shall rely
solely on the representations contained in the Prospectus and supplemental
information above mentioned. Any printed information which we furnish you other
than the Prospectus and the Fund's periodic reports

02NYC1037

and proxy solicitation material are our sole responsibility and not the
responsibility of the Fund, and you agree that the Fund shall have no liability
or responsibility to you in these respects unless expressly assumed in
connection therewith.

    8.  You agree to deliver to each of the purchasers from you a copy of the
then current Prospectus at or prior to the time of offering or sale and you
agree thereafter to deliver to such purchasers copies of the annual and interim
reports and proxy solicitation materials of the Fund. You further agree to
endeavor to obtain proxies from such purchasers. Additional copies of the
Prospectus, annual or interim reports and proxy solicitation materials of the
Fund will be supplied to you in reasonable quantities upon request.

    9.  You are hereby authorized (i) to place orders directly with the Fund or
its agent for shares of the Fund to be sold by us subject to the applicable
terms and conditions governing the placement of orders for the purchase of Fund
shares, as set forth in the Distribution Agreement, and (ii) to tender shares
directly to the Fund or its agent for redemption subject to the applicable terms
and conditions set forth in the Distribution Agreement.

    10. We reserve the right in our discretion, without notice, to suspend sales
or withdraw the offering of Shares entirely. Each party hereto has the right to
cancel this agreement upon notice to the other party.

    11. We shall have full authority to take such action as we may deem
advisable in respect of all matters pertaining to the distribution and
redemption of Fund shares. We shall be under no liability to you except for lack
of good faith and for obligations expressly assumed by us herein. Nothing
contained in this paragraph is intended to operate as, and the provisions of
this paragraph shall not in any way whatsoever constitute, a waiver by you of
compliance with any provision of the Securities Act of 1933, as amended, or of
the rules and regulations of the Securities and Exchange Commission issued
thereunder.

    12. You represent that you are a member of the National Association of
Securities Dealers, Inc. and, with respect to any sales in the United States, we
both hereby agree to abide by the Rules of Fair Practice of such Association.

    13. Upon application to us, we will inform you as to the states in which we
believe the Shares have been qualified for sale under, or are exempt from the
requirements of, the respective securities laws of such states, but we assume no
responsibility or obligation as to your right to sell Shares in any
jurisdiction.

    14. All communications to us should be sent to the address shown below. Any
notice to you shall be duly given if mailed or telegraphed to you at the address
specified by you below.

    15. This Agreement shall become effective as of the date of your acceptance
hereof, provided that you return to us promptly a signed and dated copy.

                                          MORGAN STANLEY DISTRIBUTORS INC.

                                          By:  ................................
                                             (Authorized Signature)

Please return one signed copy
of this agreement to:

Morgan Stanley Distributors Inc.
1221 Avenue of the Americas
New York, New York 10020

Accepted:

Firm Name: Morgan Stanley DW Inc.

By:  ................................

Address: 1221 Avenue of the Americas
New York, New York 10020

Date:       , 2002

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