Among medical clinic patients consulting for IBS, symptoms of psychologic distress are common, and more than half of these patients are found to have a psychiatric diagnosis in addition to bowel dysfunction. Many investigators have therefore concluded that IBS is a psychophysiologic disorder and proposed that patients with IBS be treated with psychologic techniques. However, recent studies suggest that this association may be spurious; persons in the community who have symptoms of IBS but do not consult a doctor have no more psychologic symptoms than persons without bowel symptoms. This indicates that psychologic symptoms do not cause bowel symptoms, but, instead, influence which persons with bowel symptoms will consult a physician. The bowel symptoms and the psychologic symptoms that coexist in most patients with IBS may be best thought of as comorbid conditions. Neither causes the other, but both may be serious enough to warrant treatment. Moreover, in some patients whose bowel symptoms consist of vague complaints of abdominal pain not specifically related to defecation or to changes in the frequency or consistency of bowel habits, the psychologic disorder may be primary. Psychologic stress may exacerbate IBS whether or not the patient has a psychiatric disorder, and psychologic stress may trigger acute episodes of symptoms similar to those of IBS even in persons without IBS. However, the magnitude of this correlation is modest, suggesting that only about 10% of the variation in bowel symptoms is attributable to stress. Psychologically oriented treatments have a role in the management of IBS. Most patients who consult internists about bowel symptoms have significant levels of depression and anxiety, and they tend to notice and to worry about somatic complaints more when they experience these dysphoric affects. Psychologic treatments that reduce the level of their psychologic distress also frequently reduce the frequency and severity of complaints about bowel symptoms. Tricyclic antidepressants may be tried as a first line of treatment; they have been shown to be superior to placebo for the management of abdominal pain and diarrhea but not constipation. In patients who do not show an adequate response to antidepressants, brief psychotherapy focusing on better ways of coping with current problems, hypnosis, or behavior therapy emphasizing methods of controlling reactions to stress are recommended. Controlled trials show these treatment approaches to be superior to medical management alone. It may appear paradoxical that psychologic treatments aimed at the management of emotions are so frequently found to reduce bowel symptoms, because the motility disorder responsible for the bowel symptoms may be unrelated to the psychologic symptoms that influence the patient to seek treatment.+4