31.2
I, Christopher P. Kiritsy, Chief Financial Officer of Kos Pharmaceuticals, Inc., certify that:
1.  I have reviewed this annual report on Form 10-K of Kos Pharmaceuticals, Inc;
2.  Based on my knowledge, this annual report does not contain any untrue statement of amaterial fact or omit to state a material fact necessary to make the statements made, inlight of the circumstances under which the statements were made, not misleading withrespect to the period covered by this annual report;
3.  Based on my knowledge, the financial statements, and other financial informationincluded in this annual report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, and for, theperiods presented in this annual report;
4.  The registrant’s other certifying officers and I are responsible for establishing andmaintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15eand 15d-15(e)) and internal control over financial reporting (as defined in Exchange ActRules 13a-15f and 15-15(f)) for the registrant and we have:
a.  designed such disclosure controls and procedures or caused suchdisclosure controls and procedures to be designed under our supervision to ensurethat material information relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this annual 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, toprovide reasonable assurance regarding the reliability of financial reporting andthe preparation of financial statements for external purposes in accordance withgenerally accounting principles; c.  evaluated the effectiveness of the registrant’s disclosure controls andprocedures and presented in this report our conclusions about the effectiveness ofthe disclosure controls and procedures, as of the end of the period covered by thisreport 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 the annualreport) that has materially affected, or is reasonably likely to materially affect,the registrant’s internal control over financial reporting.
5.  The registrant’s other certifying officers and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to the registrant’sauditors and the audit committee of the registrant’s board of directors (or personsperforming the equivalent function):
 a.  all significant deficiencies and material weaknesses in the design oroperation of internal control which are reasonably likely to adversely affect theregistrant’s ability to record, process, summarize and report financialinformation; and  b.  any fraud, whether or not material, that involves management or otheremployees who have a significant role in the registrant’s internal controls overfinancial reporting.
Date: March 16, 2005
/s/ Christopher P. Kiritsy