Ivermectin is a drug that many people will never have heard of. Yet thousands of villagers of all ages in communities scattered throughout the remotest parts of Africa and Latin America know its name, and some experts regard it as one of the greatest health interventions of the past 50 years. Ivermectin was brought to the commercial market place for multi-purpose use in animal health in 1981. Six years later it was registered for human use. This remarkable compound has improved the lives and productivity of billions of humans, livestock and pets around the globe, and promises to help consign to the history books two devastating and disfiguring diseases that have plagued people throughout the tropics for generations--while new uses for it are continually being found.