A new class of novel thiazole-(benz)azole derivatives was synthesized to investigate their anticancer activity. The structure of the compounds was confirmed by IR, (1)H-NMR, and MS spectral data and elemental analyses. Anticancer effect of the compounds was evaluated against A549 and C6 tumor cell lines. MTT, analysis of DNA synthesis, acridine orange/ethidium bromide staining method and analysis of caspase-3 activation assays were performed for anticancer activity investigations. Compounds 6f and 6g, which carry 5-chloro and 5-methylbenzimidazole groups showed significant anticancer activity. Potential of these compounds to direct tumor cells to apoptotic pathway, which is a precondition of anticancer action, was also observed.