Perianal fistulas occur in up to 43% of patients with Crohn disease. Diagnostic evaluation to determine the location and type of fistulas and the presence or absence of rectal inflammation is required. A combined medical and surgical approach to the management of such patients is the optimal treatment plan. Perianal abscesses must be drained. Superficial, low transsphincteric, and low intersphincteric fistulas are usually treated with fistulotomy and antibiotics. High transsphincteric, suprasphincteric, and extrasphincteric fistulas are usually treated with noncutting setons, antibiotics, and azathioprine or 6-mercaptopurine and, in many cases, infliximab.