We report the synthesis, antiproliferative activity, and SAR of novel 3-(2'-bromopropionylamino)-benzamides. Many of the benzamide compounds showed potent cytotoxicities against Molt-3 leukemia cells. Several compounds exihibited cytotoxicities (under 6.5 microM) against five solid tumor cell lines. The mechanism of action of the most potent benzamide 10l does not involve targeting on tubulin but it causes cell cycle S-phase arrest. This active S-phase arrest agent merits further investigation.