DURING the first six months of 1980, I was involved in the Indo-Chinese refugee relief effort in Thailand as a volunteer physician at Ban Vinai camp. This camp is the principal refuge of the Laotian Hmong population, who are enemies of the Communist Pathet Lao and Vietnamese governments because of the Hmong's collaboration with the United States in the war with North Vietnam. After the war, the Hmong maintained a strong resistance to Vietnam's troops until 1979, when they were defeated at Phu Bia, Laos. Now most of the Hmong are either refugees or under control of the Vietnamese occupying force, although the resistance continues on a much reduced level. Since 1976, there have been accounts by the Hmong of chemical-biological warfare activity against their fighters and their villages and in experimentation programs. Although this was not an issue at the time I was in Ban Vinai, I had evaluated