A 51-yr-old man with a history of pancreatic carcinoma was studied with [18F]fluorodeoxyglucose ([18F]FDG) and PET as part of staging for residual disease after chemotherapy. The PET study was performed during a clostridium difficile-associated diarrheal illness. Striking [18F]FDG uptake was demonstrated in the wall of the colon over its entire length. Clostridium difficile associated diarrhea and mechanisms of [18F]FDG uptake in normal and abnormal tissues are briefly reviewed and a mechanism for FDG uptake in this patient is postulated.