Introduction: Methylthiosemicarbazones (MTSCs) are compounds with various biological properties. Some studies have shown that their metal complexes have potential cytotoxic effects on numerous cancers. In this study, the effects of zinc (II)-methylthiosemicarbazone complex (Zn-MTC) on the human chronic myelogenous leukemia K562 cell line were evaluated. 
Methods: In this experimental study, K562 cells were treated with different doses of Zn-MTC for 24, 48, and 72 hours. We investigated whether this compound could induce cytotoxicity and apoptosis in K562 cells using the MTT assay, fluorescence microscopy, and flow cytometry. 
Results: Our findings indicated that Zn-MTC inhibited the growth of K562 cells and induced apoptosis in a time- and dose-dependent manner. The IC50 of the complex was 100 µM after 72 hours of incubation. Morphological changes and sub-G1 cell cycle arrest confirmed the induction of apoptosis in K562 cells treated with the IC50 concentration of this compound. 
Conclusion: Given its antiproliferative and apoptosis-inducing effects, Zn-MTC can be proposed for further pharmaceutical evaluation in the treatment of chronic myeloid leukemia (CML) in the future