A series of 1,5-diarylimidazoles with 4-methylsulfonylphenyl group were prepared and evaluated for the inhibitory activities against COX-2 catalyzed PGE(2) production from LPS-induced RAW 264.7 cells. Most of synthesized 1,5-diarylimidazoles exhibited strong inhibitory activities regardless of the position of the 4-methylsulfonylphenyl group. The 1,5-diarylimidazoles with a halogen atom (3c-3h, 3n-3p) gave mostly excellent inhibitory activities regardless of the position and species of the halogen atom. Whereas the 1,5-diarylimidazoles with two fluorine atoms (3k, 3l, 3r, 3s) showed rather reduced inhibitory activities.