The synthesis of a series of 3-[5-(substituted aryl)-1,3,4-oxadiazol-2-yl]-1-(biphenyl-4-yl)propan-1-ones derived from 4-oxo-4-(biphenyl-4-yl)butanoic acid (fenbufen) is described. The structures of these compounds were supported by IR, (1)H NMR, mass spectrometric data and elemental analysis. These compounds were tested for their antiinflammatory, analgesic, ulcerogenic and lipid peroxidation actions. A few compounds were found to have very good antiinflammatory activity in carrageenan induced rat paw edema test, while a fair number of compounds showed significant analgesic activity in acetic acid induced writhing test. The newly synthesized compounds showed very low ulcerogenic action with reduced malondialdehyde (MDA) content, which is one of the byproducts of lipid peroxidation. In vitro COX-1 and COX-2 isozyme inhibition studies were also performed on some of the selected compounds. Compound 4i and 4h were found to be more selective towards COX-2 as indicated by COX-2 selectivity index of 36.06 and 29.05 (COX-2 IC(50)=1.5 microM and 1.8 microM) respectively.