The 20th anniversary of the Bhopal calamity fell on December 3, 2004. The world's worst industrial disaster in Bhopal, India, happened because of inadequate maintenance by Union Carbide and poor monitoring by the Indian authorities. Malfunctioning safety measures, inappropriate location of the plant, and lack of information about the identity and toxicity of the gas worsened the effects of the accident on people and livestock. The Bhopal disaster has raised questions about the implications of the transfer of potentially hazardous technology to the developing countries. Even after 20 years, Bhopal has not recovered. In this article, we present what happened and why and what lessons can be learned at this terrible cost.