In this study, a series of pyrazole-sulfonamide derivatives were designed and synthesized from 1-(4-aminophenyl)-4-benzoyl-5-phenyl-N-(5-sulfamoyl-1,3,4- thiadiazol-2-yl)-1H-pyrazole-3-carboxamide (1). The newly synthesized sulfonamides were characterized by FT-IR, 1 H NMR, 13 C NMR, and elemental analyses. The compounds were tested for their in vitro antiproliferative activities against HeLa and C6 cell lines. The tests were carried out as dose-dependent assay starting from 5 to 100 μg/mL. All compounds showed especially cell selective effect against rat brain tumor cells (C6). Some of the tested compounds (3) and (7) showed promising broad spectrum antitumor activity comparable to the activities of the commonly used anticancer drugs, 5-fluorouracil and cisplatin. © 2013 Springer Science+Business Media New York.