The irritable colon syndrome is a very common disorder with no serious sequelae. The cause is unknown but low dietary bulk and psychological factors are believed important. Sufferers may experience various combinations of diarrhea, constipation and abdominal pain. The mechanisms are obscure but abnormal colon motility has been amply demonstrated. Serious organic diseases such as colitis and carcinoma of the colon must be firmly excluded. Treatment consists of sympathetic explanation and reassurance, increased dietary bulk and occasional judicious use of antispasmodic agents.