A series of methysulfonyl or sulfonamido substituted 4,5-diaryloxazole were prepared and evaluated for their ability to inhibit the inducible form of cyclooxygenase (COX-2) in vitro and in vivo. Several unique substitution patterns were identified that led to potent and selective inhibitors of COX-2. In general, 2-trifluoromethly-4,5-diaryloxazoles substituted with a methylsulfonyl or sulfonamido group were particularly potent inhibitors. One of the more potent compounds with a selectivity for COX-2 of about 800 fold was 4b (SC-299). SC-299, a highly fluorescent molecule, may be useful for spectroscopic studies on preferential inhibitor binding to COX-2.