Perianal disease is a frequent manifestation of Crohn's disease and occasionally is the presenting symptom. However, most lesions are or become asymptomatic and remain so for many years. A series of 109 patients with perianal fissures and fistulas has baeen followed for 10 years. Fourteen have died, 7 from unrelated disorders. Ten have had an excision of the rectum but only 5 for perianal disease. Of the remaininga 85 patients, 24 asymptomatic patients were not re-examined, and 61 were investigated extensively by sigmoidoscopy biopsy or manometry. Many fissures and most fistulas had healed, but some had progressed to some degree of anal stenosis, usually asymptomatic. A very conservative policy is proposed.