During their disease course, the majority of Crohn's disease patients will develop a complicated disease which is characterized by the occurrence of fistulas and/or stenosis. Symptomatic, perianal fistulas should be surgically drained before anti-inflammatory therapy will be initiated. Antibiotics, such as metronidazole, improve disease symptomatic however, they are not sufficient to induce continuous fistula closure. For this purpose, azathioprine/6-mercaptopurine as well as anti-TNF antibodies are useful when administered continuously. Surgical options include seton drainage, fistula excision, fistula plugs and mucosa flaps. As ultima ratio, temporary ileostomy and proctectomy are to be discussed. Non-perianal fistulas often require surgical approaches. Symptomatic strictures or stenosis can be treated by anti-inflammatory medications (only if they are cause by inflammation), endoscopic balloon dilatation or surgery.