EXHIBIT 1.1


                        INVESCO UNIT TRUSTS, SERIES 1599

                                TRUST AGREEMENT

                            Dated: November 3, 2015

   This Trust Agreement among Invesco Capital Markets, Inc., as Depositor, The
Bank of New York Mellon, as Trustee, and Invesco Investment Advisers LLC, as
Supervisor, sets forth certain provisions in full and incorporates other
provisions by reference to the document entitled "Standard Terms and Conditions
of Trust For Invesco Unit Trusts, Effective for Unit Investment Trusts
Established On and After December 6, 2012 (Including Invesco Unit Trusts, Series
1281 and Subsequent Series)" (the "Standard Terms and Conditions of Trust") and
such provisions as are set forth in full and such provisions as are incorporated
by reference constitute a single instrument. All references herein to Articles
and Sections are to Articles and Sections of the Standard Terms and Conditions
of Trust.

                                WITNESSETH THAT:

   In consideration of the premises and of the mutual agreements herein
contained, the Depositor, Trustee and Supervisor agree as follows:

                                     PART I

                     STANDARD TERMS AND CONDITIONS OF TRUST

   Subject to the provisions of Part II hereof, all the provisions contained in
the Standard Terms and Conditions of Trust are herein incorporated by reference
in their entirety and shall be deemed to be a part of this instrument as fully
and to the same extent as though said provisions had been set forth in full in
this instrument.

                                    PART II

                     SPECIAL TERMS AND CONDITIONS OF TRUST

   The following special terms and conditions are hereby agreed to:

   1. The Securities listed in the Schedule hereto have been deposited in trust
under this Trust Agreement.

   2. The fractional undivided interest in and ownership of the Trust
represented by each Unit thereof referred to in Section 1.01(51) is initially an
amount the numerator of which is one and the denominator of which is the amount
set forth under "Units outstanding" for the Trust in the "Statement of
Condition" in the Prospectus.

   3. The terms "Capital Account Distribution Date" and "Income Account
Distribution Date" shall mean the "Distribution Dates" set forth in the
"Essential Information" in the Prospectus.

   4. The terms "Capital Account Record Date" and "Income Account Record Date"
shall mean the "Record Dates" set forth in the "Essential Information" in the
Prospectus.

   5. The term "Deferred Sales Charge Payment Date" shall mean April 10, 2016
and the tenth day of each month thereafter through August 10, 2016.

   6. The Depositor's annual compensation rate described in Section 3.13 and the
Supervisor's annual compensation rate described in Section 4.01 collectively
shall be that amount set forth under "Supervisory, bookkeeping and
administrative fees" in the "Fee Table" in the Prospectus.

   7. The Trustee's annual compensation rate described in Section 7.04 shall be
that amount set forth under "Trustee's fee and operating expenses" in the "Fee
Table" in the Prospectus.

   8. Notwithstanding anything to the contrary in the Standard Terms and
Conditions of Trust, if the Trustee sells, redeems or otherwise liquidates Fund
Shares pursuant to Section 6.02 to satisfy Unit redemptions or pursuant to
Section 7.04 to pay Trust expenses, the Trustee shall do so, as nearly as
practicable, on a pro rata basis among all Fund Shares held by a Trust.

   IN WITNESS WHEREOF, the undersigned have caused this Trust Agreement to be
executed; all as of the day, month and year first above written.


                         INVESCO CAPITAL MARKETS, INC.

                            By: /s/ JOHN F. TIERNEY
                            -----------------------
                                 Vice President


                        INVESCO INVESTMENT ADVISERS LLC

                            By: /s/ JOHN F. TIERNEY
                            -----------------------
                     Vice President and Executive Director


                          THE BANK OF NEW YORK MELLON

                           By: /s/ JOANNA YEDREYESKI
                           -------------------------
                                 Vice President




                         SCHEDULE A TO TRUST AGREEMENT

                         SECURITIES INITIALLY DEPOSITED
                                       IN
                        INVESCO UNIT TRUSTS, SERIES 1599

      [Incorporated herein by this reference and made a part hereof is the
             "Portfolio" schedule as set forth in the Prospectus.]