A novel series of 2-acetamido-or 2-propanamido-4-(4-substituted phenyl)-1, 3-thiazoles (11– 34) was designed and synthesized. Compounds were subjected to National Cancer Institute (NCI) in vitro assessment for their antitumor activity, at a single dose of 10μM. Most of the investigated compounds exhibited broad-spectrum antitumor activity. Compounds 19 and 28 believed to be the most active members in this study, with MG-MID GI50, TGI, and LC50 ...