Cancer is a disease of uncontrolled cell growth and proliferation that is predicted to directly affect 1 in 3 Canadians. Standard chemotherapy that targets DNA or its replicative machinery effectively eradicates cancer cells, but also causes non-specific toxicity to healthy cells. Pancratistatin, a natural alkaloid isolated from Hymenocallis littoralis, was found to selectively induce apoptosis (programmed cell death) in many types of human cancer cells, with an insignificant effect on healthy non-cancerous cells. Major findings presented in this work are: the selectivity and efficacy of pancratistatin and synthetic derivatives on patient-obtained and commercially available leukemia, the potent effect of pancratistatin on human colon and prostate cancer cells in vitro and in vivo, and the unique mechanism of action of pancratistatin. In summary, pancratistatin is a natural anti-cancer compound that selectively targets cancer cell mitochondria to induce apoptosis and significantly reduces growth of human tumor xenografts.