Diagnostic radiology has assumed an increasingly prominent role in the diagnosis, investigation, and treatment of gastrointestinal fistulas during the past 15 years. This development largely has been the result of the application of computed tomography and ultrasonography to the diagnosis of intra-abdominal inflammatory processes and the use of these cross-sectional imaging modalities to guide percutaneous abscess drainage by the interventional radiologist. Effective percutaneous techniques have been developed that allow many gastrointestinal fistulas to be managed nonoperatively with less morbidity and mortality.