Cytotoxicity of organotin (IV) compounds towards various types of cancerous cells have been extensively studied by researchers worldwide. In this study,two new organotin (IV) compounds; diphenyltin (IV) ethylphenyldithiocarbamate (DFEF) and diphenyltin (IV) butylphenyldithiocarbamate (DFBF) were used to evaluate their cytotoxic effect against erythroleukemia cells, K562. K562 cell was used as target cell whereas Chang liver and V79 fibroblast cells were used to evaluate the effects of both compounds on non-cancerous cells. The cytotoxic effects of both compounds were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at 24, 48 and 72 hours using different concentrations. Observations on the morphological changes were carried out with IC50 value for times of exposure similar to the MTT assay test. The cytotoxicity test showed that, DFEF and DFBF compounds were very toxic toward K562 cells with the IC50 values obtained less than 10 μM at all times of exposure. The selectivity index have proven that both compounds exhibited selective cytotoxic effect against K562 cells at 48 and 72 hours, meanwhile at 24 hours, these compounds showed general toxicity towards K562 and non-cancerous cells. We found that both compounds were toxic to non-cancerous cells, Chang liver and V79 cells where the IC50 values were less than 5 μM. Both compounds also showed selectivity to target cell at 48 and 72 hours of exposure. However for 24 hours, these compounds showed general toxicity and non-selective cytotoxic effect towards K562 cells and non-cancerous cells. The morphological changes match with characteristic of apoptosis such as cell shrinkage and formation of apoptotic bodies, also necrosis such as lysis of cells. In conclusion, diphenyltin (IV) alkylphenyldithiocarbamate showed great potential to be a good anti-leukemic agent. However, its specific mechanism of action in K562 cells should be further studied to elucidate its potential as a new anticancer drug