Summary Intraventricular administration of enterotoxin did not produce vomiting. Chemoreceptor trigger zone ablation in cats did not affect the emetic response to intravenous enterotoxin. Transthoracic vagotomy raised the threshold for enterotoxin-induced emesis. Midbrain transection abolished the emetic response. The possibility was considered that the emetic stimulus provided by enterotoxin traverses afferent pathways that are concerned in vomiting responses to x-radiation and nitrogen mustard.