New 4-(4-phenylsubstituted)-1,2,3-triazolacetic acid derivatives of general formula (I) were prepared by nucleophilic substitution, 1,3-dipolar cycloaddition and functional group interconversion reactions. These compounds were evaluated as in vitro prostaglandin synthesis inhibitors. Only the isomeric compounds (II c) and (III e), with a 4-aminophenyl substituent on the triazole ring, inhibit arachidonic acid-induced malondialdehyde formation in human platelets; (II c) and (III e) are as effective as aspirin.