Some novel 2-(substitutedbenzylthio)-5-((2- (4-substitutedpheny1)-1H-benzo[d]imidazol-1-yl)methyl)-1,3,4-oxadiazoles (5-12) and 2-(2-(4-chlorophenyl)-1H-benzo[d] imidazol-1-yl)-N'-(arylmethylene)acetohydrazide derivatives (13-22) were prepared and their in vitro antioxidant properties were investigated by determination of rat liver microsomal NADPH-dependent inhibition of lipid peroxidation (LP) levels and microsomal ethoxyresorufin O-deethylase (EROD) activity. Compound 18 was found to be the most active compound with 100% inhibition on LP level and 92% inhibition on EROD. Compounds 4b, 17, and 19 showed the strongest inhibitory effect (97%) on EROD. The free radical scavenging capacities of the compounds were also tested in vitro determining the interaction of the stable free radical 2,2,diphenyl-1-picrylhydrazyl (DPPH), and compounds 4a and 4b exhibited good antioxidant activities.