EXHIBIT 4.3


                          CAPSTEAD MORTGAGE CORPORATION

                    FORM OF JUNIOR SUBORDINATED NOTE DUE 2035

[IF THIS SECURITY IS A GLOBAL SECURITY INSERT: THIS SECURITY IS A GLOBAL
SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS
REGISTERED IN THE NAME OF THE DEPOSITORY TRUST COMPANY ("DTC") OR A NOMINEE OF
DTC. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A
PERSON OTHER THAN DTC OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED
IN THE INDENTURE, AND NO TRANSFER OF THIS SECURITY (OTHER THAN A TRANSFER OF
THIS SECURITY AS A WHOLE BY DTC TO A NOMINEE OF DTC OR BY A NOMINEE OF DTC TO
DTC OR ANOTHER NOMINEE OF DTC) MAY BE REGISTERED EXCEPT IN LIMITED
CIRCUMSTANCES.

UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF DTC TO THE
ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
SECURITY ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT HEREON IS MADE
TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.]

THE SECURITIES REPRESENTED BY THIS CERTIFICATE WERE ORIGINALLY ISSUED IN A
TRANSACTION EXEMPT FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"), AND SUCH SECURITIES, AND ANY INTEREST THEREIN,
MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF ANY
SECURITIES IS HEREBY NOTIFIED THAT THE SELLER OF THE SECURITIES MAY BE RELYING
ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED
BY RULE 144A UNDER THE SECURITIES ACT.

THE HOLDER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE AGREES FOR THE
BENEFIT OF THE COMPANY THAT (A) SUCH SECURITIES MAY BE OFFERED, RESOLD OR
OTHERWISE TRANSFERRED ONLY (I) TO THE COMPANY OR (II) TO A PERSON WHOM THE
SELLER REASONABLY BELIEVES IS A "QUALIFIED PURCHASER" (AS DEFINED IN SECTION
2(a)(51) OF THE INVESTMENT COMPANY ACT OF 1940, AS AMENDED), AND (B) THE

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HOLDER WILL NOTIFY ANY PURCHASER OF ANY SECURITIES FROM IT OF THE RESALE
RESTRICTIONS REFERRED TO IN (A) ABOVE.

THE SECURITIES WILL BE ISSUED AND MAY BE TRANSFERRED ONLY IN BLOCKS HAVING AN
AGGREGATE PRINCIPAL AMOUNT OF NOT LESS THAN $100,000. TO THE FULLEST EXTENT
PERMITTED BY LAW, ANY ATTEMPTED TRANSFER OF SECURITIES, OR ANY INTEREST THEREIN,
IN A BLOCK HAVING AN AGGREGATE PRINCIPAL AMOUNT OF LESS THAN $100,000 AND
MULTIPLES OF $1,000 IN EXCESS THEREOF SHALL BE DEEMED TO BE VOID AND OF NO LEGAL
EFFECT WHATSOEVER. TO THE FULLEST EXTENT PERMITTED BY LAW, ANY SUCH PURPORTED
TRANSFEREE SHALL BE DEEMED NOT TO BE THE HOLDER OF SUCH SECURITIES FOR ANY
PURPOSE, INCLUDING, BUT NOT LIMITED TO, THE RECEIPT OF PRINCIPAL OF OR INTEREST
ON SUCH SECURITIES, OR ANY INTEREST THEREIN, AND SUCH PURPORTED TRANSFEREE SHALL
BE DEEMED TO HAVE NO INTEREST WHATSOEVER IN SUCH SECURITIES.

THE HOLDER OF THIS SECURITY, OR ANY INTEREST THEREIN, BY ITS ACCEPTANCE HEREOF
OR THEREOF ALSO AGREES, REPRESENTS AND WARRANTS THAT IT IS NOT AN EMPLOYEE
BENEFIT, INDIVIDUAL RETIREMENT ACCOUNT OR OTHER PLAN OR ARRANGEMENT SUBJECT TO
TITLE I OF THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED
("ERISA"), OR SECTION 4975 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE
"CODE") (EACH A "PLAN"), OR AN ENTITY WHOSE UNDERLYING ASSETS INCLUDE "PLAN
ASSETS" BY REASON OF ANY PLAN'S INVESTMENT IN THE ENTITY, AND NO PERSON
INVESTING "PLAN ASSETS" OF ANY PLAN MAY ACQUIRE OR HOLD THIS SECURITY OR ANY
INTEREST THEREIN. ANY PURCHASER OR HOLDER OF THE SECURITIES OR ANY INTEREST
THEREIN WILL BE DEEMED TO HAVE REPRESENTED BY ITS PURCHASE AND HOLDING THEREOF
THAT IT IS NOT AN EMPLOYEE BENEFIT PLAN WITHIN THE MEANING OF SECTION 3(3) OF
ERISA, OR A PLAN TO WHICH SECTION 4975 OF THE CODE IS APPLICABLE, A TRUSTEE OR
OTHER PERSON ACTING ON BEHALF OF AN EMPLOYEE BENEFIT PLAN OR PLAN, OR ANY OTHER
PERSON OR ENTITY USING THE ASSETS OF ANY EMPLOYEE BENEFIT PLAN OR PLAN TO
FINANCE SUCH PURCHASE.

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                          CAPSTEAD MORTGAGE CORPORATION

                        JUNIOR SUBORDINATED NOTE DUE 2035

No. _____________                                                   $ 36,083,000

            Capstead Mortgage Corporation, a corporation organized and existing
under the laws of Maryland (hereinafter called the "Company," which term
includes any successor Person under the Indenture hereinafter referred to), for
value received, hereby promises to pay to Wells Fargo Bank, National
Association, not in its individual capacity but solely as Property Trustee of
Capstead Mortgage Trust I, or registered assigns, the principal sum of Thirty
Six Million Eighty Three Thousand Dollars ($36,083,000) [IF THE SECURITY IS A
GLOBAL SECURITY, THEN INSERT -- OR SUCH OTHER PRINCIPAL AMOUNT REPRESENTED
HEREBY AS MAY BE SET FORTH IN THE RECORDS OF THE SECURITIES REGISTRAR
HEREINAFTER REFERRED TO IN ACCORDANCE WITH THE INDENTURE] on October 30, 2035.
The Company further promises to pay interest on said principal sum from
September 26, 2005, or from the most recent Interest Payment Date to which
interest has been paid or duly provided for, quarterly in arrears on January 30,
April 30, July 30 and October 30, of each year, commencing October 30, 2005, or
if any such day is not a Business Day, on the next succeeding Business Day (and
no interest shall accrue in respect of the amounts whose payment is so delayed
for the period from and after such Interest Payment Date until such next
succeeding Business Day), except that, if such Business Day falls in the next
succeeding calendar year, such payment shall be made on the immediately
preceding Business Day, in each case, with the same force and effect as if made
on the Interest Payment Date, at a fixed rate equal to 8.19% per annum through
the interest payment date on October 30, 2015 ("Fixed Rate Period") and
thereafter at a variable rate equal to LIBOR plus 3.5% per annum, together with
Additional Tax Sums, if any, as provided in Section 10.5 of the Indenture, until
the principal hereof is paid or duly provided for or made available for payment;
provided, further, that any overdue principal, premium, if any, or Additional
Tax Sums and any overdue installment of interest shall bear Additional Interest
at a fixed rate equal to 8.19% through the interest payment date on October 30,
2015 and thereafter at a variable rate equal to LIBOR plus 3.5% per annum (to
the extent that the payment of such interest shall be legally enforceable),
compounded quarterly, from the dates such amounts are due until they are paid or
made available for payment, and such interest shall be payable on demand.

            The amount of interest payable on any Interest Payment Date shall be
computed during the Fixed Rate Period on the basis of a 360-day year of twelve
30-day months, and thereafter on the basis of a 360-day year and the actual
number of days elapsed in the relevant interest period. The interest so payable,
and punctually paid or duly provided for, on any Interest Payment Date shall, as
provided in the Indenture, be paid to the Person in whose name this Security (or
one or more Predecessor Securities) is registered at the close of business on
the Regular Record Date for such interest installment. Any such interest not so
punctually paid or duly provided for shall forthwith cease to be payable to the
Holder on such Regular Record Date and may either be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on a Special Record Date for the payment of such Defaulted
Interest to be fixed by the Trustee, notice whereof shall be given to Holders of
Securities not less than ten (10)

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days prior to such Special Record Date, or be paid at any time in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities may be listed, and upon such notice as may be required
by such exchange, all as more fully provided in the Indenture.

            During an Event of Default, the Company shall not (i) declare or pay
any dividends or distributions on, or redeem, purchase, acquire or make a
liquidation payment with respect to, any of the Company's capital stock or (ii)
make any payment of principal of or any interest or premium, if any, on or
repay, repurchase or redeem any debt securities of the Company that rank pari
passu in all respects with or junior in interest to this Security (other than
(a) repurchases, redemptions or other acquisitions of shares of capital stock of
the Company in connection with (1) any employment contract, benefit plan or
other similar arrangement with or for the benefit of any one or more employees,
officers, directors or consultants, (2) a dividend reinvestment or stockholder
stock purchase plan and (3) the issuance of capital stock of the Company (or
securities convertible into or exercisable for such capital stock) as
consideration in an acquisition transaction entered into prior to such Event of
Default, (b) as a result of an exchange or conversion of any class or series of
the Company's capital stock (or any capital stock of a Subsidiary of the
Company) for any class or series of the Company's capital stock or of any class
or series of the Company's indebtedness for any class or series of the Company's
capital stock, (c) the purchase of fractional interests in shares of the
Company's capital stock pursuant to the conversion or exchange provisions of
such capital stock or the security being converted or exchanged, (d) any
declaration of a dividend in connection with any Rights Plan, the issuance of
rights, stock or other property under any Rights Plan, or the redemption or
repurchase of rights pursuant thereto or (e) any dividend in the form of stock,
warrants, options or other rights where the dividend stock or the stock issuable
upon exercise of such warrants, options or other rights is the same stock as
that on which the dividend is being paid or ranks pari passu with or junior to
such stock).

            Payment of principal of, premium, if any, and interest on this
Security shall be made in such coin or currency of the United States of America
as at the time of payment is legal tender for payment of public and private
debts. Payments of principal, premium, if any, and interest due at the Maturity
of this Security shall be made at the Place of Payment upon surrender of such
Securities to the Paying Agent, and payments of interest shall be made, subject
to such surrender where applicable, by wire transfer at such place and to such
account at a banking institution in the United States as may be designated in
writing to the Paying Agent at least ten (10) Business Days prior to the date
for payment by the Person entitled thereto unless proper written transfer
instructions have not been received by the relevant record date, in which case
such payments shall be made by check mailed to the address of such Person as
such address shall appear in the Security Register. Notwithstanding the
foregoing, so long as the Holder of this Security is the Property Trustee, the
payment of the principal of (and premium, if any) and interest (including any
overdue installment of interest and Additional Tax Sums, if any) on this
Security will be made at such place and to such account as may be designated by
the Property Trustee.

            The indebtedness evidenced by this Security is, to the extent
provided in the Indenture, subordinate and junior in right of payment to the
prior payment in full of all Senior Debt, and this Security is issued subject to
the provisions of the Indenture with respect thereto. Each Holder of this
Security, by accepting the same, (a) agrees to and shall be bound by such
provisions, (b)

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authorizes and directs the Trustee on his or her behalf to take such actions as
may be necessary or appropriate to effectuate the subordination so provided and
(c) appoints the Trustee his or her attorney-in-fact for any and all such
purposes. Each Holder hereof, by his or her acceptance hereof, waives all notice
of the acceptance of the subordination provisions contained herein and in the
Indenture by each holder of Senior Debt, whether now outstanding or hereafter
incurred, and waives reliance by each such holder upon said provisions.

            Unless the certificate of authentication hereon has been executed by
the Trustee by manual signature, this Security shall not be entitled to any
benefit under the Indenture or be valid or obligatory for any purpose.

                          [FORM OF REVERSE OF SECURITY]

            This Security is one of a duly authorized issue of securities of the
Company (the "Securities") issued under the Junior Subordinated Indenture, dated
as of September 26, 2005 (the "Indenture"), between the Company and Wells Fargo
Bank, National Association, as Trustee (in such capacity, the "Trustee," which
term includes any successor trustee under the Indenture), to which Indenture and
all indentures supplemental thereto reference is hereby made for a statement of
the respective rights, limitations of rights, duties and immunities thereunder
of the Company, the Trustee, the holders of Senior Debt, the Holders of the
Securities and the holders of the Preferred Securities, and of the terms upon
which the Securities are, and are to be, authenticated and delivered.

            All terms used in this Security that are defined in the Indenture or
in the Amended and Restated Trust Agreement, dated as of September 26, 2005 (as
modified, amended or supplemented from time to time, the "Trust Agreement"),
relating to the Capstead Mortgage Trust I (the "Trust") among the Company, as
Depositor, the Trustees named therein and the Holders from time to time of the
Trust Securities issued pursuant thereto, shall have the meanings assigned to
them in the Indenture or the Trust Agreement, as the case may be.

            The Company may, on any Interest Payment Date, at its option, upon
not less than thirty (30) days' nor more than sixty (60) days' written notice to
the Holders of the Securities (unless a shorter notice period shall be
satisfactory to the Trustee) on or after October 30, 2010 and subject to the
terms and conditions of Article XI of the Indenture, redeem this Security in
whole at any time or in part from time to time at a Redemption Price equal to
one hundred percent (100%) of the principal amount hereof, together, in the case
of any such redemption, with accrued interest, including any Additional
Interest, through but excluding the date fixed as the Redemption Date.

            In addition, upon the occurrence and during the continuation of a
Special Event, the Company may, at its option, upon not less than thirty (30)
days' nor more than sixty (60) days' written notice to the Holders of the
Securities (unless a shorter notice period shall be satisfactory to the
Trustee), redeem this Security, in whole but not in part, subject to the terms
and conditions of Article XI of the Indenture at a Redemption Price equal to one
hundred seven and one half percent (107.5%) of the principal amount hereof,
together, in the case of any such redemption, with accrued interest, including
any Additional Interest, through but excluding the date fixed as the Redemption
Date.

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            In the event of redemption of this Security in part only, a new
Security or Securities for the unredeemed portion hereof will be issued in the
name of the Holder hereof upon the cancellation hereof. If less than all the
Securities are to be redeemed, the particular Securities to be redeemed shall be
selected not more than sixty (60) days prior to the Redemption Date by the
Trustee from the Outstanding Securities not previously called for redemption, by
such method as the Trustee shall deem fair and appropriate and which may provide
for the selection for redemption of a portion of the principal amount of any
Security.

            The Indenture permits, with certain exceptions as therein provided,
the Company and the Trustee at any time to enter into a supplemental indenture
or indentures for the purpose of modifying in any manner the rights and
obligations of the Company and of the Holders of the Securities, with the
consent of the Holders of not less than a majority in principal amount of the
Outstanding Securities. The Indenture also contains provisions permitting
Holders of specified percentages in principal amount of the Securities, on
behalf of the Holders of all Securities, to waive compliance by the Company with
certain provisions of the Indenture and certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the Holder of
this Security shall be conclusive and binding upon such Holder and upon all
future Holders of this Security and of any Security issued upon the registration
of transfer hereof or in exchange herefor or in lieu hereof, whether or not
notation of such consent or waiver is made upon this Security.

            No reference herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the
Company, which is absolute and unconditional, to pay the principal of and any
premium, if any, and interest, including any Additional Interest (to the extent
legally enforceable), on this Security at the times, place and rate, and in the
coin or currency, herein prescribed.

            As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of this Security is restricted to transfers to
"Qualified Purchasers" (as such term is defined in the Investment Company Act of
1940, as amended), and is registrable in the Securities Register, upon surrender
of this Security for registration of transfer at the office or agency of the
Company maintained for such purpose, duly endorsed by, or accompanied by a
written instrument of transfer in form satisfactory to the Company and the
Securities Registrar and duly executed by, the Holder hereof or such Holder's
attorney duly authorized in writing, and thereupon one or more new Securities,
of like tenor, of authorized denominations and for the same aggregate principal
amount, will be issued to the designated transferee or transferees.

            The Securities are issuable only in registered form without coupons
in minimum denominations of $100,000 and any integral multiple of $1,000 in
excess thereof. As provided in the Indenture and subject to certain limitations
therein set forth, Securities are exchangeable for a like aggregate principal
amount of Securities and of like tenor of a different authorized denomination,
as requested by the Holder surrendering the same.

            No service charge shall be made for any such registration of
transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith.

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            The Company, the Trustee and any agent of the Company or the Trustee
may treat the Person in whose name this Security is registered as the owner
hereof for all purposes, whether or not this Security be overdue, and neither
the Company, the Trustee nor any such agent shall be affected by notice to the
contrary.

            The Company and, by its acceptance of this Security or a beneficial
interest herein, the Holder of, and any Person that acquires a beneficial
interest in, this Security agree that, for United States federal, state and
local tax purposes, it is intended that this Security constitute indebtedness.

            THIS SECURITY SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF THE STATE OF NEW YORK, WITHOUT REFERENCE TO ITS CONFLICT
OF LAWS PROVISIONS (OTHER THAN SECTION 5-1401 OF THE GENERAL OBLIGATIONS LAW).

            IN WITNESS WHEREOF, the Company has caused this instrument to be
duly executed on this ___ day of _________, 20__.

                                    Capstead Mortgage Corporation


                                    By:
                                       ----------------------------------------
                                       Name:
                                            -----------------------------------
                                       Title:
                                             ----------------------------------

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