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 annual report
on Form 10-K of the Company for the fiscal year ended January 31, 2008;

2.

Based on my
knowledge, this annual 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;

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-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 Company and we 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 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;

(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
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

(d)

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 (the Company's
fourth fiscal quarter in the case of an annual report) that has materially
affected, or is reasonably likely to materially affect the Company's internal
control over financial reporting: and

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 financial reporting which are reasonably likely to adversely affect
the Company's ability to record, process, summarize and report financial
information; and

(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: April 30, 2008 | /s/ George G. Usher                
|--------------------- | -----------------------------------
|                      | Chief Executive
    Officer        
|                      | Polydex
    Pharmaceuticals Limited

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