A 60-year-old woman with a remote history of colon carcinoma was studied with F-18 FDG PET imaging 5 days after admission for acute toxigenic enterocolitis. Marked and diffusely increased uptake was noticed throughout the ascending and transverse colon, which was noticed to be edematous and thickened on contrast CT examination. The study emphasizes the need to consider nonneoplastic entities, such as enterocolitis in the differential diagnosis of intensely hypermetabolic colonic lesions on F-18 FDG PET examinations.