The legacy of the human misery caused by the application of the herbicides including Agent Blue, the arsenic-based herbicide, sprayed over the jungles, rice fields, and hamlets of Vietnam, is still haunting us more than fifty years after the end of the Vietnam War. The United States and other countries need to learn the historical lessons from our use of a herbicide, containing arsenic, as chemical weapons during the Vietnam and Second Indochina War. Only by understanding the past can future misapplication of new weapons be prevented.