**EXHIBIT 31.1**

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**CERTIFICATIONPURSUANT TO**

**SECTION 302(a) OFTHE SARBANES-OXLEY ACT OF 2002**

** **

I,Nicholas Konidaris, certify that:

 

1.               I have reviewed thisquarterly report on Form 10-Q of Electro Scientific Industries, Inc.;

 

2.               Based on my knowledge,this report does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this report;

 

3.               Based on my knowledge,the financial statements, and other financial information included in thisreport, fairly present in all material respects the financial condition,results of operations and cash flows of the registrant as of, and for, theperiods presented in this report;

 

4.               The registrant’s othercertifying officer and I are responsible for establishing and maintainingdisclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant andhave:

 

(a)          Designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision, toensure that material information relating to the registrant, including itsconsolidated 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 suchinternal control over financial reporting to be designed under our supervision,to provide reasonable assurance regarding the reliability of financialreporting and the preparation of financial statements for external purposes inaccordance with generally accepted accounting principles;

 

(c)          Evaluated the effectiveness of the registrant’s disclosure controls andprocedures and presented in this report our conclusions about the effectivenessof the disclosure controls and procedures, as of the end of the period coveredby this report based on such evaluation; and

 

(d)         Disclosed in this report any change in the registrant’s internalcontrol over financial reporting that occurred during the registrant’s most recentfiscal quarter (the registrant’s fourth fiscal quarter in the case of an annualreport) that has materially affected, or is reasonably likely to materiallyaffect, the registrant’s internal control over financial reporting; and

 

5.               The registrant’s other certifying officer andI have disclosed, based on our most recent evaluation of internal control overfinancial reporting, to the registrant’s auditors and the audit committee ofthe registrant’s board of directors (or persons performing the equivalentfunctions):

 

(a)          All significant deficiencies and material weaknesses in the design oroperation of internal control over financial reporting which are reasonablylikely to adversely affect the registrant’s ability to record, process,summarize and report financial information; and

 

(b)         Any fraud, whether or not material, that involves management or otheremployees who have a significant role in the registrant’s internal control overfinancial reporting.

 
| Date: September 22, 2005         |
|---------------------------------------|
|                                  |
| /s/ Nicholas Konidaris                |   |
| Nicholas Konidaris                    |
| President and Chief Executive Officer |

 

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