Fistulas are common in Crohn's disease. A population-based study has shown a cumulative risk of 33% after 10 years and 50% after 20 years. Perianal fistulas were the most common (54%). Medical therapy is the main option for perianal fistula once abscesses, if present, have been drained, and should include antibiotics ( both ciprofloxacin and metronidazole) and immunomodulators. Infliximab should be reserved for refractory patients. Surgery is often necessary for internal fistulas. Copyright (C) 2005 S. Karger AG, Basel.