We conducted a clinical study of 137 patients with home-canned bamboo shoot botulism at Nan Hospital, northern Thailand. The median age of the patients was 44 years (range = 14-74 years) and 36.2% were male. The median incubation period was 2 days (range = 1-8 days). Forty-three patients (31.4%) developed respiratory failure, but there were no deaths. Patients who did not have either nausea or vomiting and did not have urinary retention that required Foley catheterization was less likely to develop respiratory failure. This clinical predictor rule had a sensitivity of 75.5% and a specificity of 90.7%. The clinical syndrome most predictive of respiratory failure was nausea or vomiting and any cranial neuropathy with urinary retention or difficulty swallowing. This clinical syndrome had a sensitivity of 69.8% and a specificity of 93.6%. These clinical characteristics could help triage large numbers of patient in the event of a future outbreak.