A new series of 4-aryl-4H-chromenes bearing a 2-arylthiazol-4-yl moiety at the 4-position were prepared as potential cytotoxic agents. The in-vitro cytotoxic activity of the synthesized 4-aryl-4H-chromenes was investigated in comparison with etoposide, a well-known anticancer drug, using MTT colorimetric assay. Among them, the 2-(2-chlorophenyl)thiazol-4-yl analog 4b showed the most potent activity against nasopharyngeal epidermoid carcinoma KB, medulloblastoma DAOY, and astrocytoma 1321N1, and compound 4d bearing a 2-(4-chlorophenyl)thiazol-4-yl moiety at the 4-position of the chromene ring exhibited the best inhibitory activity against breast cancer cells MCF-7, lung cancer cells A549, and colon adenocarcinoma cells SW480 with IC(50 )values less than 5 microM. The ability of compound 4b to induce apoptosis was confirmed in a nuclear morphological assay by DAPI staining in the KB and MCF-7 cells.