In order to investigate the effect of simvastatin and irinotecan combination on the apoptosis of colon cancer cells with or without resistance, we performed cell death detection ELISA tests and caspase-3 activity assay on HT-29 and HT-29R cells treated with simvastatin or irinotecan alone or the combination of simvastatin and irinotecan at 2 : 1 molar ratio. The gene discussed is CASP3; the disease is colonic neoplasm.