Anal fistula surgery offers very little in the way of new developments. As early as the 14th century John of Arden defined the rules for surgical therapy. The numerous classifications adopted are often contradictory and unclear, and no clearly defined pathogenesis of the condition has been established. Complex anal fistula with a recess above the elevator ani muscles requires very careful and meticulous therapeutic treatment because of the risk of damaging the sphincter. In the case reported here the patient presented a very complex fistula which was followed by onset of severe haemorrhagic colitis without any clinical, endoscopic, radiological, or histological evidence of inflammatory bowel disease prior to surgical treatment.