1H-Indole-2,3-dione (isatin) is an endogenous compound identified in many organisms, possesses a wide range of biological activities. Biological properties of isatin include a range of actions in brain and offer protection against certain types of infections. This molecule has a versatile moiety that displays diverse biological activities, including anticancer activity. The discovery of numerous biologically active 3-substituted 2-indolinones led in the past decade to extensive synthesis of related compounds and as a result, anticancer agents were developed. In particular, among the 5-substituted analogs tested in the growth inhibitions against several human cancer cell lines, 5-halide, methoxy and trifluoromethoxy groups containing 3-substituted 2-indolinones show high antiproliferative effects. For this purpose, we first synthesized twelve 5-fluoro-1H-indole-2,3-dione-3-thiosemicarbazones that antituberculosis activities were shown previously by our teamwork and we researched anticancer drug potential in this study. The cytotoxic effects of twelve thiosemicarbazone derivatives were investigated by MTT assay in chronic myeloid leukemia cell lines (K562, HL60), B-lymphoma cell lines (P3HR1) and in vincristine resistant forms. The IC50values (IC50is a concentration that kills 50% of cells) were calculated from dose-response curve according to cytotoxicity index. The effectiveness of thiosemicarbazone derivatives were evaluated by comparing IC50values in leukemic cell lines. All of the compounds were found cytotoxic in B-lymphoma cell lines (P3HR1, P3HR1Vin) in range 0.95–2.41 μM. However, the allyl derivative of thiosemicarbazones has cytotoxic activity in all the cancer cell lines (K562, K562Vin, HL-60, P3HR1, P3HR1Vin) that were tested. As a result, 5-fluoro-1H-indole-2,3-dione-3-thiosemicarbazones derivates might have chemotherapeutic drug potential in B-lymphoma patients. The allyl derivative of thiosemicarbazones has benefit both B-lymphoma and chronic myeloid leukemia patients in a large spectrum.