At an annual religious rite in Nawaimai village, Nan province, Thailand, villagers became ill and sought medical care. The illnesses progressed to include bulbar muscle paralysis, with respiratory depression requiring ventilatory support. At that time, a botulism outbreak was suspected. On the basis of clinical manifestations of the patients and results of the epidemiologic investigation, the most probable cause of the illnesses was botulinum toxin from Clostridium botulinum. Samples of the leftover, canned bamboo shoots were cultured and grew Clostridium botulinum, toxin A. Due to the size of this outbreak which overwhelmed the medical care system and the lack of botulism antitoxin within the country, the Thai government requested international assistance.