By 1996, the median survival of patients with cystic fibrosis (CF) in North America had increased to 31 years. With the markedly improved life expectancy, many CF patients are now adults. There is an associated increased risk of certain colonic disorders, and the emergence of other previously unrecognized disorders, in adult CF patients. The distal intestinal obstruction syndrome (DIOS), which is more common in older patients, is a frequent cause of abdominal pain. Intussusception may complicate DIOS; other differential diagnoses include appendiceal disease, volvolus, Crohn's disease, fibrosing colonopathy and colonic carcinoma. The diagnosis of acute appendicitis, although uncommon in patients with CF, is often delayed, and appendiceal abscess is a frequent complication. The prevalence of Crohn's disease in CF has been shown to be 17 times that of the general population. Right-sided microscopic colitis is a recently recognized entity in CF of uncertain clinical significance. Fibrosing colonopathy has been confined mostly to children with CF, attributed to the use of high strength pancreatic enzyme supplements, but it has been reported in three adults. Nine cases of carcinoma of the large intestine have been reported worldwide, associated with an apparent excess risk of digestive tract cancers in CF. Despite high carrier rates ofClostridium difficilein patients with CF, pseudomembranous colitis is distinctly rare, but severe cases complicated by toxic megacolon have been reported. In these patients, watery diarrhea is often absent. Adult CF patients with refractory or unexplained intestinal symptoms merit thorough investigations.