Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.