**Exhibit  31.1**

**Rule  13a-14(a)/15d-14(a) Certification**

| I,      Matthew H. Knight, certify that: |
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|                                     | 1.  | I      have reviewed this Quarterly Report on Form 10-Q of Strategic Diagnostics      Inc. (the “registrant”); |
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|                                     | 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; |
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|                                     | 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; |
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|                                     | 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)) for the registrant and      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 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; |
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|                                     |   | b) | 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; and |
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|                                     |   | c) | 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      (the registrant’s fourth fiscal quarter in the case of an annual report)      that has materially affected, or is reasonably likely to materially affect,      the registrant’s internal control over financial reporting; and |
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|                                     | 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 the registrant’s board of directors      (or persons performing the equivalent function): |
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|                                     |   | 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; 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 registrant’s internal control over financial      reporting. |

 

|   |             | /s/      Matthew H. Knight   |   |
|--------|------------------|------------------------------|--------|
|   |             |                              |   |
|        |                  | Matthew      H. Knight       |   |
|        |                  | Chief Executive      Officer |   |
| Date:  | November 5, 2004 |                         |   |
|   |                  |                         |   |

 

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