A number of 1,4-dihydropyridine derivatives (9a-d, 10a-d, and 11a-d) were designed and synthesized by the reaction of 1,3,4-oxadiazole-5-thiones and 1,2,4-triazole-5-thiones to 2,6-dibromomethyl-3,5-diethoxycarbonyl-4-(3-ni-trophenyl)-1,4-dihydropyridine. The synthesized compounds were characterrized using FT-IR, 1H-NMR, 13C-NMR spectral data, ESI-MS, and elemental analysis. The cytotoxicity of the synthesized compounds was evaluated in human breast cancer (MCF-7) cells based on the results of MTT assay. The results indicated that compound Diethyl 4-(3-nitrophenyl)-2,6-bis[((5-(3-nitrophenyl)-1,3,4-oxa-diazol-2-yl)thio)methyl]-1,4-dihydro pyridine-3,5-dicarboxylate (9b) with (IC50 = 23 ? 2.32 ?M) was the most potent derivative against MCF-7 cells. Based on the results, the use of oxadiazole moiety in the C2 and C6 positions of 1,4-di-hydropyridine ring system enhanced the cytotoxic potential of these derivatives. Therefore, some of the oxadiazole-substituted 1,4-DHPs may facilitate further modifications which result in the discovery of potent cytotoxic agents.