Abstract: Twenty-eight condensation products of heterocycle-α-carboaldehydes with N-aminooxazolidones, semicarbazides, thiosemicarbazides, aminoguanidines,aromatic hydrazides and benzoxycarbonyl hydrazide were synthesized so as to deduce the antiulcer pharmacophore or fragment of furazolidone(Ⅰ), the prototype,which shows therapeutic efficacy for patients with gastric ulcer.Analysis of the SAR of the compounds indicate that the substitution of furan, thiophene, pyrrole and N-methyl pyrrole rinks for the 5-nitrofuran and the cleavage of the oxazolidon (?)ain the activity to some extent. The necessary electronic desity of carbonyl group of compounds is of importance. A lead structure, therefore, is derived for further optimization.