A review of the health effects of the 1984 gas leak from the Union Carbide plant in Bhopal, India, shows continuing morbidity of a multisystemic nature in the exposed population. Scientific debates about the causes of the accident, the spectrum of health effects, and toxicology are presented with a view to understanding the toxic substances released in the gas cloud and their roles in the causation of health effects. Clinical dilemmas, medical management, and public health issues are also discussed.