An unusual case of an anorectal fistula presenting with hip pain and extensive lower limb muscle wasting in a patient with Crohn's disease is reported. This report emphasizes the important role of a thorough history, a complete physical examination, and a thorough search for evaluating such cases. Any progressive local irritation and pain in a Crohn's disease patient may indicate possible fistulous involvement. Nonspecific laboratory findings such as leukocytosis, anemia, decreased albumin level, and thrombocytosis may be considered as supportive indicators. Barium contrast studies and enhanced computed tomography scan may be helpful but can be falsely negative in the presence of a fistula, as in this case. These findings illustrate that the clinician must not be dissuaded from the diagnosis simply based on negative radiological findings because the presence of a fistula may be impossible to determine preoperatively.