A series of 5-(2'-indolyl)thiazoles were synthesized and evaluated for their cytotoxicity against selected human cancer cell lines. The reaction of thioamides 3 with 3-tosyloxypentane-2,4-dione 4 led to in situ formation of 5-acetylthiazole 5 which upon treatment with arylhydrazines 6 in polyphosphoric acid resulted in the formation of 5-(2'-indolyl)thiazoles 2. Among the synthesized 5-(2'-indolyl)thiazoles, compounds 2d-f, and 2h exhibited encouraging anticancer activity and also selectivity towards particular cell lines (IC50 = 10-30 μM). Further studies on the SAR of compound 2e may result in good anticancer activity.