Post-transplantation lymphoprotiferative disorder (PTLD) is a serious complication of chronic immunosuppression following solid organ transplantation. Clinical presentation is non-specific and almost any organ can be affected. Early diagnosis is associated with a better prognosis but requires tissue sampling to ascertain the histopathological subtype of disease which cannot be predicted on imaging features atone. The radiologist has a key role in detecting the disorder, guiding biopsy and monitoring response to treatment which often only involves a reduction in immunosuppressive therapy. The aim of this paper is to illustrate the wide spectrum of imaging features in PTLD and emphasize the more specific findings which allow the diagnosis to be suggested at an early stage. (C) 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.