A patient with botulism was studied at different times after intoxication using various autonomic tests of the cardiovascular reflexes, and by single fiber EMG (SFEMG). The control of heart rate and blood pressure appeared markedly impaired in the early stage of the disease as well as SFEMG. Autonomic function recovered more slowly as neuromuscular transmission. Monitoring autonomic derangement in botulism may give the opportunity to select patients at risk for cardiac or respiratory arrest.