A series of newly synthesized organotin (IV) with N-alkyl-N-phenyldithiocarbamate ligands namely triphenyltin (IV) ethylphenyldithiocarbamate (compound 1) and triphenyltin (IV) butylphenyldithiocarbamate (compound 2) were assessed for their cytotoxic effect against HT-29 human colon adenocarcinoma cells and human CCD-18Co normal colon cells. The cytotoxicity of these organotins in both cells was assessed using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazholium bromide (MTT) assay upon 24 h treatment. Both compounds demonstrated potent cytotoxicity towards HT-29 cells with the IC 50 of 0.18 µM for compound 1 and 0.20 µM for compound 2. Interestingly, compound 1 exhibited lower cytotoxicity towards CCD-18Co with IC 50 of 1.55 µM whereas no IC 50 was detected for compound 2 up to 2 µM treatment. The mode of cell death was determined based on the externalization of phosphatidylserine using flow cytometry. Cells treated with compound 1 and compound 2 were mainly viable and the apoptotic cell death was around 10% which suggests that both compounds induced growth arrest. In conclusion, this study demonstrated that both compounds were selective towards human colorectal cells by giving a strong cytotoxicity to cancer cells and low toxicity towards normal cells. Both compounds were suggested to induce growth arrest in HT-29 cells.