A psychological etiology or predisposition for cyclic vomiting syndrome (CVS) has long been suspected. Much of the psychiatric literature to date has blamed patients or their families for the problem or focused on psychoanalytic interpretation to account for the syndrome. Thirty-two patients with CVS were compared with 64 age- and sex-matched controls. The patients had a higher incidence of psychological symptoms and migraine. On the Achenbach Child Behavior Checklist patients had higher internalizing, somatic complaints, and anxiety/depression scores. CVS is a migraine variant, with attacks usually precipitated by stress and intercurrent infections. The psychological characteristics of patients with CVS probably contribute to their vulnerability.