The so-called superior-mesenteric-artery syndrome is not mentioned in psychiatric journals or books. Yet two variations of the condition have been described. In its acute form, it can be mistaken for psychogenic vomiting in anorexic patients, while its chronic intermittent form is readily misdiagnosed as anorexia nervosa. The case report is of a 16 year old boy admitted for investigation and treatment of severe weight loss. He initially responded to a modified behaviour program, but within days developed an acute small-bowel obstruction. Superior-mesenteric-artery syndrome was diagnosed and he improved with appropriate medical management. This condition needs to be considered by the psychiatrist who otherwise might not differentiate it from the symptoms of anorexia nervosa.