Women who are of normal weight and have bulimia nervosa have multiple neuroendocrine disturbances. The reasons for these neuroendocrine abnormalities are not known, but there are reasons to suspect that bingeing and vomiting behavior could be contributory. It is well known that food consumption in healthy volunteers increases plasma insulin, cortisol, and prolactin secretion and suppresses growth hormone secretion, whereas activation of the emetic reflex increases plasma arginine vasopressin (AVP) secretion. The purpose of this study was to investigate the effects of bingeing and vomiting on these hormones. In comparison with healthy control women consuming a large meal, bulimic patients, when bingeing and vomiting, had an exaggerated secretion of either the amount and/or the duration of insulin, cortisol, and prolactin. Vasopressin secretion was not increased during or after bingeing and vomiting, probably because bulimic subjects do not become nauseated. In addition, bulimic patients had significantly reduced baseline plasma prolactin and possibly elevated baseline cortisol compared with controls. In summary, this study supports the presence of neuroendocrine disturbances in bulimia and raises a question as to whether or not excessive and prolonged food consumption (and/or vomiting) are contributory.