Oxaliplatin as an effective chemotherapeutic agent in FOLFOX regimens is using to treat colorectal cancer. In this study we investigate cytotoxicity of Oxaliplatin as single chemotherapeutic agent toHCT116P53+/- to identify molecular mechanism of Oxaliplatin action in induction of apoptosis pathway. Oxaliplatin exposure to HCT116P53+/- colorectal cell lines with deficiency of mismatch repair characteristic resulted to decrease the number of viable cells through apoptosis. Effective Oxaliplatin concentrations (IC50) which inhibit 50% of cell viability were determined using XTT method. Standard curve and time-dependent assay performed to confirm IC50 concentration. Western blot analysis demonstrated relocalization of Bax to mitochondria and induction of intrinsic apoptosis pathway resulted Oxaliplatin exposure. Inactivation of Bax in HCT116P53+/- will result significant reduction in number of viable cells following treatment with Oxaliplatin