Cyclic vomiting is a psychosomatic syndrome, but it is also a diagnosis of exclusion. Before such a diagnosis can be made, an organic basis for the episodes of vomiting must be ruled out. We describe a case of episodic vomiting in a school-aged girl. Endoscopic examination eventually confirmed a diagnosis of intermittent duodenal intussusception due to an enteric duplication. Removal of the duplication abolished the episodes of vomiting. The differential diagnosis of episodic vomiting is discussed, and the literature on intussusception is reviewed. Endoscopy should be considered in a child with a history of episodic vomiting.