The irritable bowel syndrome is a common chronic disorder having a broad clinical spectrum of severity. Although only a small proportion of those afflicted seek medical help for their symptoms, a subset have severe and intractable symptoms. A positive diagnosis should be established from the history and physical examination; endoscopic and radiologic investigations should be minimized. We suggest that the physician also assess the severity of the illness based on its symptomatic and functional features and the patient's behavioral response. Classifying the disorder in this manner permits a graduated treatment approach that emphasizes education, reassurance, and dietary adjustment for mild symptoms. Moderate symptom severity requires, in addition, identification and modification of factors exacerbating symptoms, psychotherapeutic and behavioral techniques and, if a certain symptom type predominates, pharmacologic agents directed toward the presumed gastrointestinal motor dysfunction. For severe symptoms, physician-based behavior modification and psychopharmacologic agents are helpful. When the disorder is intractable, referral may be needed, for example, to a pain treatment center. In all cases, the skillful physician must ensure continued psychosocial support to enhance coping and continued focus on the palliative aspects of care rather than on cure.