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EXHIBIT 31.1 CAPSTEAD MORTGAGE CORPORATION
CERTIFICATION PURSUANT TO SECTION 302(a)
OF THE SARBANES-OXLEY ACT OF 2002 I, Andrew F. Jacobs, certify that:  1.
    
    I have reviewed this Quarterly Report on Form 10-Q of Capstead Mortgage
Corporation;2.
    
    Based on my knowledge, this report does not contain any untrue statement
of a material fact or omit to state a material fact necessary to make the
statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this
report;3.
    
    Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material
respects the financial condition, results of operations and cash flows of
the registrant as of, and for, the periods presented in this report;4.
    
    The registrants other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as
defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal
control over financial reporting (as defined in Exchange Act Rules
13a-15(f) and 15d-15(f)) for the registrant and have:  a)
    
    Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our
supervision, to ensure that material information relating to the
registrant, including its consolidated subsidiaries, is made known to
us by others within those entities, particularly during the period in
which this report is being prepared;b)
    
    Designed such internal control over financial reporting, or caused
such internal control over financial reporting to be designed under our
supervision, to provide reasonable assurance regarding the reliability
of financial reporting and the preparation of financial statements for
external purposes in accordance with generally accepted accounting
principles;c)
    
    Evaluated the effectiveness of the registrants disclosure controls
and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures as of the end
of the period covered by this report based on such evaluation; andd)
    
    Disclosed in this report any change in the registrants internal
control over financial reporting that occurred during the registrants
most recent fiscal quarter that has materially affected, or is
reasonably likely to materially affect, the registrants internal
control over financial reporting; and  5.
    
    The registrants other certifying officer and I have disclosed, based on
our most recent evaluation of internal control over financial reporting,
to the registrants auditors and the audit committee of registrants board
of directors:  a)
    
    All significant deficiencies and material weaknesses in the design
or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrants ability to
record, process, summarize and report financial information; andb)
    
    Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrants
internal control over financial reporting. Date: October 29, 2004
    By:
    /s/ ANDREW F. JACOBSAndrew F. JacobsPresident and Chief Executive Officer