<PAGE>

                                                                    EXHIBIT 4.16

                                 TRUST AGREEMENT
                                       OF
                          BANCORPSOUTH CAPITAL TRUST II

         THIS TRUST AGREEMENT, dated as of October 31, 2001 (this "Trust
Agreement"), is made by and among BancorpSouth, Inc., a Mississippi corporation,
as depositor (the "Depositor"), The Bank of New York (Delaware), a Delaware
banking corporation, as trustee (the "Delaware Trustee"), The Bank of New York,
a New York banking corporation, as trustee (the "Property Trustee"), and Aubrey
B. Patterson, and L. Nash Allen, Jr., as trustees (the "Administrative Trustees"
and, together with the Delaware Trustee and the Property Trustee, the
"Trustees"). The Depositor and the Trustees hereby agree as follows:

         1. The trust created hereby shall be known as "BancorpSouth Capital
Trust II" (the "Trust"), in which name the Trustees or the Depositor, to the
extent provided herein, may conduct the business of the Trust, make and execute
contracts, and sue and be sued.

         2. The Depositor hereby assigns, transfers, conveys and sets over to
the Trust the sum of $10. The Trust hereb y acknowledges receipt of such amount
in trust from the Depositor, which amount shall constitute the initial trust
estate. The Trustees hereby declare that they will hold the trust estate in
trust for the Depositor. It is the intention of the parties hereto that the
Trust created hereby constitute a business trust under Chapter 38 of Title 12 of
the Delaware Code, 12 Del. C. ss. 3801, et seq. (the "Business Trust Act"), and
that this document constitutes the governing instrument of the Trust. The
Trustees are hereby authorized and directed to execute and file a certificate of
trust with the Delaware Secretary of State in accordance with the provisions of
the Business Trust Act.

         3. The Depositor and the Trustees will enter into an amended and
restated Trust Agreement, satisfactory to each such party and substantially in
the form to be included as an exhibit to the 1933 Act Registration Statement (as
defined below), to provide for the contemplated operation of the Trust created
hereby and the issuance of the Preferred Securities and Common Securities
referred to therein. Prior to the execution and delivery of such amended and
restated Trust Agreement, the Trustees shall not have any duty or obligation
hereunder or with respect to the trust estate, except as otherwise required by
applicable law or as may be necessary to obtain prior to such execution and
delivery any licenses, consents or approvals required by applicable law or
otherwise.

         4. The Depositor, as the sponsor of the Trust, is hereby authorized, in
its discretion, (i) to prepare and file with the Securities and Exchange
Commission (the "Commission") and to execute, in each case on behalf of the
Trust, (a) the Registration Statement on Form S-3 or other appropriate form (the
"1933 Act Registration Statement"), including the prospectus and the exhibits
included therein, any pre-effective or post-effective amendments thereto and any
registration statements filed subsequent thereto under Rule 462(b) promulgated
under the Securities Act of 1933, as amended (the "1933 Act"), relating to the
registration under the 1933 Act of the Preferred Securities of the Trust and
certain other securities, (b) any preliminary prospectus or prospectus or
supplement thereto relating to the Preferred Securities of the Trust required to
be filed pursuant to the 1933 Act, and (c) a Registration Statement on Form 8-A
or other appropriate form (the "1934 Act Registration Statement"), including all
pre-effective and post-effective amendments thereto, relating to the
registration of the Preferred Securities of the Trust under the Securities


<PAGE>

Exchange Act of 1934, as amended (the "1934 Act"), and such other documents,
forms or filings as may be required by the 1933 Act, the 1934 Act, or the Trust
Indenture Act of 1939, as amended, in each case relating to the Preferred
Securities of the Trust; (ii) to prepare and file with the New York Stock
Exchange or other exchange (each, an "Exchange") or the National Association of
Securities Dealers ("NASD") and execute on behalf of the Trust a listing
application or applications and all other applications, statements,
certificates, agreements and other instruments as shall be necessary or
desirable to cause the Preferred Securities of the Trust to be listed on any
such Exchange or the NASD's Nasdaq National Market; (iii) to file and execute on
behalf of the Trust such applications, reports, surety bonds, irrevocable
consents, appointments of attorney for service of process and other papers and
documents as the Depositor, on behalf of the Trust, may deem necessary or
desirable to register, or establish the exemption from registration of, the
Preferred Securities of the Trust under the securities or "Blue Sky" laws of
such jurisdictions as the Depositor, on behalf of the Trust, may deem necessary
or desirable; (iv) to execute and deliver letters or documents to, or
instruments for filing with, a depository relating to the Preferred Securities
of the Trust; and (v) to execute, deliver and perform on behalf of the Trust one
or more underwriting agreements with one or more underwriters, purchase
agreements, dealer manager agreements, escrow agreements and other documents and
agreements, in each case relating to the offering of the Preferred Securities of
the Trust as the Depositor, on behalf of the Trust, may deem necessary or
desirable. In the event that any filing referred to in clauses (i), (ii) and
(iii) above is required by the rules and regulations of the Commission, any
Exchange, the NASD or state securities or "Blue Sky" laws, to be executed on
behalf of the Trust by one or more of the Trustees, any of the Trustees, in
their capacity as trustees of the Trust, are hereby authorized to join in any
such filing and to execute on behalf of the Trust any and all of the foregoing,
it being understood that the Trustees, in their capacity as trustees of the
Trust, shall not be required to join in any such filing or execute on behalf of
the Trust any such document unless required by the rules and regulations of the
Commission, any Exchange, the NASD or state securities or "Blue Sky" laws.

         5. This Trust Agreement may be executed in one or more counterparts.

         6. The number of trustees of the Trust initially shall be four (4) and
thereafter the number of trustees of the Trust shall be such number as shall be
fixed from time to time by a written instrument signed by the Depositor which
may increase or decrease the number of trustees of the Trust; provided, however,
that to the extent required by the Business Trust Act, one trustee of the Trust
shall either be a natural person who is a resident of the State of Delaware or,
if not a natural person, an entity which has its principal place of business in
the State of Delaware and otherwise meets the requirements of applicable
Delaware law. Subject to the foregoing, the Depositor is entitled to appoint or
remove without cause any trustee of the Trust at any time. Any trustee of the
Trust may resign upon thirty (30) days' prior notice to the Depositor provided,
however, such notice shall not be required if it is waived by the Depositor.

         7. The Delaware Trustee, in its capacity as trustee of the Trust, shall
not have any of the powers or duties of the Trustees set forth herein (except as
may be required under the Business Trust Act) and shall be a trustee of the
Trust for the sole and limited purpose of fulfilling the requirements of Section
3807 of the Business Trust Act.


<PAGE>

         8. The Depositor hereby agrees to (i) reimburse the Trustees for all
reasonable expenses (including reasonable fees and expenses of counsel and other
experts), and (ii) indemnify, defend and hold harmless the Trustees and any of
the officers, directors, employees and agents of the Trustees (the "Indemnified
Persons") from and against any and all losses, damages, liabilities, claims,
actions, suits, costs, expenses, disbursements (including the reasonable fees
and expenses of counsel), taxes and penalties of any kind and nature whatsoever
(collectively, "Expenses"), to the extent that such Expenses arise out of or are
imposed upon or asserted at any time against such Indemnified Persons with
respect to the performance of this Trust Agreement, the creation, operation or
termination of the Trust or the transactions contemplated hereby; provided,
however, that the Depositor shall not be required to indemnify any Indemnified
Person for any Expenses which are a result of the willful misconduct, bad faith
or gross negligence of such Indemnified Person.

         9. The Trust may be dissolved and terminated before the issuance of the
Preferred Securities of the Trust at the election of the Depositor.

         10. This Trust Agreement shall be governed by, and construed in
accordance with, the laws of the State of Delaware (without regard to conflict
of laws principles).


<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement
to be duly executed as of the day and year first above written.

                                    BANCORPSOUTH, INC.,
                                    as Depositor



                                    By:    /s/ L. Nash Allen, Jr.
                                           ------------------------------------
                                    Name:  L. Nash Allen, Jr.
                                           ------------------------------------
                                    Title: Treasurer and Chief Financial Officer
                                           ------------------------------------

                                    THE BANK OF NEW YORK (DELAWARE),
                                    as Delaware Trustee



                                    By:    /s/ William T. Lewis
                                           ------------------------------------
                                    Name:
                                           ------------------------------------
                                    Title: WILLIAM T. LEWIS, SVP
                                           ------------------------------------

                                    THE BANK OF NEW YORK,
                                    as Property Trustee



                                    By:    /s/ Robert A. Massimillo
                                           ------------------------------------
                                    Name:  Robert A. Massimillo
                                           ------------------------------------
                                    Title: VICE PRESIDENT
                                           ------------------------------------



                                    /s/ Aubrey B. Patterson
                                    -------------------------------------------
                                    Aubrey B. Patterson,
                                    as Administrative Trustee



                                    /s/ L. Nash Allen, Jr.
                                    -------------------------------------------
                                    L. Nash Allen, Jr.,
                                    as Administrative Trustee