Patients with irritable bowel syndrome (IBS) (n = 121) were compared to 46 patients with inflammatory bowel disease (IBD), and to 45 nonpatient controls on a variety of psychological tests and on symptomatology. The most consistent finding was the ordering of group psychological test means such that, on 11 of 14 measures, IBS patients scored higher than IBD patients, who in turn scored higher than the nonpatient controls. The two patient groups differed significantly only on measures of anxiety with the IBS patients scoring significantly higher on all three measures. IBS patients also reported significantly more severity of abdominal pain than the IBD patients; while IBD patients reported more episodes of diarrhea, they did not rate them as significantly more severe than did the IBS patients. Various other parameters of the IBS population are also explored and implications for treatment and future study are discussed.