Structured psychiatric interviews and psychological self-report measures were administered to 28 patients with irritable bowel syndrome and 19 patients with inflammatory bowel disease. Significantly more of the patients with irritable bowel syndrome had lifetime diagnoses of major depression, somatization disorder, generalized anxiety disorder, panic disorder, and phobic disorder. They had significantly more medically unexplained somatic symptoms, and most had suffered from psychiatric disorders, particularly anxiety disorders, before the onset of their irritable bowel symptoms.