Irritable bowel syndrome (IBS) is a common chronic, relapsing functional bowel disorder. IBS can be diagnosed according to the established series of criteria excluding organic diseases, and by institution of a therapeutic trial. Treatment should be tailored to individual patients' needs and fears. Education and reassuring the patients is a simple and effective form of therapy. Correction of precipitating factors can also be therapeutic. Some patients may be helped by changing the diet, avoiding certain drugs, and reducing life stressors. Symptomatic treatment includes fiber for constipation, loperamide for diarrhea, and low-dose antidepressants or antispasmodics for pain; therapeutic efficacy of novel modalities including drugs acting on serotonin receptors are under investigation.