Post-transplant lymphoproliferative disease (PTLD) is a major cause of morbidity and mortality following both solid organ and haematopoietic stem cell transplantation. PTLD has a broad range of manifestations with extranodal involvement more common in the abdomen than nodal involvement. Fludeoxyglucose positron emission tomography/CT (FDG-PET/CT) is sensitive and specific to detect PTLD and can upstage or detect occult PTLD compared with conventional CT imaging. As functional imaging, FDG-PET/CT also has a role in monitoring treatment response. In this pictorial essay, we will discuss the role of FDG-PET/CT in the diagnosis and staging of abdominal PTLD and describe the advantages of functional imaging in assessing response to therapy.