The Vietnam War was fought in a jungle environment that provided cover to the enemy and made battlefield observations difficult, so military strategists used herbicides to remove foliage along key roads and waterways, defoliate areas surrounding enemy bases and supply and communications routes, and improve visibility in heavily canopied forests. The last three decades have seen an ongoing debate about the effects of this military use of herbicides and the potential adverse long-term health effects on those who may have been exposed to these herbicides. In response to these concerns, the Air Force Health Study (AFHS) was created to investigate the potential relationship between the herbicides used and the health problems of those exposed. Disposition of the Air Force Health Study assesses the scientific merit of the AFHS operations and procedures, and makes recommendations for improvement.