4-Pivaloyloxy, 4-benzenesulfonyloxy and 4-ρ-toluenesulfonyloxy compounds of piroxicam (2a, 2b and 2c) and isoxicam(4a, 4b and 4c) were synthesized in fairly good yield. Antiinflammatory and ulcerogenic effects of the 6 compounds were determined. Antiinflammatory effect of 2a was comparable to that of piroxicam and ulcerogenic effect of 2a was less than that of piroxicam.