Various diagnostic modalities have been introduced for the diagnostic work-up of suspected pancreatic cancer. However, the differentiation of pancreatic cancer and chronic pancreatitis is still a challenge. Positron emission tomography (PET) with radiolabeled fluorodeoxyglucose (FDG) is an imaging modality that is based on the increased glucose metabolism of malignant cells. In contrast to conventional imaging, which provides morphological information, FDG-PET demonstrates functional alterations of malignant tumours. The value of FDG-PET in differentiating pancreatic lesions has been validated by numerous studies with variable patient selection criteria. In these studies a sensitivity between 71% and 100% and a specificity between 64% and 100% was reported. The median sensitivity was 92% and the median specificity 82%. The diagnostic accuracy was limited in hyperglycemic patients and in patients with active inflammation of the pancreas, as is found in acute pancreatitis or active chronic pancreatitis. These limitations have to be taken into account for the indication of FDG-PET as well as the interpretation of PET findings.