In this study, a series of 1,3,4-thiadiazole (1b-9b) and l,2,4-triazole-3-thione (1c-9c) derivatives were synthesized. The reaction proses was carried out with the cyclocondensation of suitable 1,4-disubstituted thiosemicarbazide derivatives (1a-9a). The structures of the synthesized compounds were confirmed by the data obtained from elemental analysis, HPLC, UV, IR, 1 H-NMR and MS spectra. All of the compounds were tested for their cytotoxic activities against L929 fibroblast cells by MTT method. It was determined that the tested compounds 1a-9a, 1b-9b and 1c-9c were not cytotoxic at the studied concentrations (5.0 µg/mL and 10.0 µg/mL) in L929 cell lines. Compounds 1a-c, 2a-c, 3a-c, 4a-c, 5a-c and 8a-c showed increased growth inhibition whereas compounds 6a-c, 7a-c and 9a-c showed decreased growth inhibition on L929 cell lines