In Northeast Thailand, khai mak mai (fruit fever) is a local, ethnomedical category of illness identified by community members as untreatable by biomedical health providers. The illness is believed to be incompatible with several substances that may induce death, including fruit as well as two forms of medication associated with biomedical care: injections and intravenous solution. Consequently, fevers suspected of being khai mak mai are treated by herbalists while biomedical health services are avoided and feared. In this article, I examine local perceptions and treatment of khai mak mai. I also explore the context and consequences of concerns about the inadequacy of biomedical care, as well as the social meanings associated with the illness and the political-economic context that shapes both the meanings of, and everyday responses to, fevers suspected of being khai mak mai.