**Exhibit 31.1**

 

**CERTIFICATION**

 

**Certification of Principal Executive Officer**

 

I,William C. Dow, certify that:

 

1.               I have reviewedthis annual report on Form 10-K of Aksys, Ltd.;

 

2.               Based on myknowledge, this  report does not containany untrue statement of a material fact or omit to state a material factnecessary to make the statements made, in light of the circumstances underwhich such statements were made, not misleading with respect to the periodcovered by this annual report;

 

3.               Based on myknowledge, the financial statements, and other financial information includedin this report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, andfor, the periods presented in this report;

 

4.               Theregistrant’s other certifying officer and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange ActRules 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 registrantand have:

 

a)                                      designed such disclosure controlsand procedures, or caused such disclosure controls and procedures to bedesigned under our supervision, to ensure that material information relating tothe registrant, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which this  report is being prepared;

 

b)                                     designed such internal control overfinancial reporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonable assurance regardingthe reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally acceptedaccounting principles;

 

c)                                      evaluated the effectiveness of theregistrant’s disclosure controls and procedures and presented in this reportour conclusions about the effectiveness of the disclosure controls andprocedures, as of the end of the period covered by this report based on suchevaluation; and

 

d)                                     disclosed in this report any changein the registrant’s internal control over financial reporting that occurredduring the registrant’s most recent fiscal quarter that has materially affected,or is reasonably likely to materially affect, the registrant’s internal controlover financial reporting; and

 

5.               Theregistrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to theregistrant’s auditors and the audit committee of the registrant’s board ofdirectors (or persons performing the equivalent functions):

 

a)                                      all significant deficiencies andmaterial weaknesses in the design or operation of  internal control over financial reportingwhich are reasonably likely to adversely affect the registrant’s ability torecord, 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 theregistrant’s internal control over financial reporting.

 

 
| Dated: | March 16, 2005 | By:    | /s/ William C. Dow                     |   |
|--------|----------------|--------|----------------------------------------|--------|
|   |           |   | William  C. Dow                        |
|   |           |   | President  and Chief Executive Officer |

 

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