# Exhibit 31.1

# CERTIFICATION

I, George G. Usher, Chief Executive
Officer of Polydex Pharmaceuticals Limited (the "Company") do hereby certify
that:

| | 1. | I
have reviewed this quarterly report on Form 10-Q of the Company for the fiscal quarter
ended April 30, 2005;
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| | 2. | Based
on my  knowledge,  this  quarterly  report does not contain any untrue  statement of a
material fact or omit to  state  a material fact necessary in order 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 Company as of, and for,  the period presented in this
report;
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| | 4. | The
Companys other certifying officer and I are responsible for  establishing and
maintaining disclosure controls and procedures (as defined in  Exchange Act Rules 13a14
and 15d14) for the Company and we have:
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| |  | (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  Company,  including its consolidated subsidiaries, is made known to us
by others  within those  entities, particularly during the period in which this report
was  being prepared;
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| |  | (b) | evaluated
the effectiveness of the Company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;
and
| |  | --- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| |  | (c) | disclosed
in this report any change in the Companys internal control over  financial
reporting that occurred during the Companys most recent fiscal  quarter that has
materially affected, or is reasonably likely to materially  affect the Companys
internal control over financial reporting; and
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| | 5. | The
Companys other certifying officer and I have disclosed, based on our  most recent
evaluation, to the Companys auditors and the audit committee  of the Companys
board of directors:
| | -- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| |  | (a) | all
significant deficiencies and  material weaknesses in the  design or operation of internal
control over reporting  which are reasonably likely to adversely affect the Companys
ability to record,  process, summarize and report financial information; and
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| |  | (b) | any
fraud, whether or not material, that involves management or other employees  who have a
significant role in the Companys internal control over  financial reporting.
| |  | --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Dated:  June 14, 2005

| | /s/ George G. Usher                                   
| | ------------------------------------------------------
| | Chief Executive OfficerPolydex Pharmaceuticals Limited

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