Progressive multifocal leukoencephalopathy (PML) is a demyelinating infection caused by the JC virus. It is an emerging disease in transplant recipients; however, it remains poorly defined. Twenty-four cases of PML reported in the literature in transplant recipients were reviewed. Of the 24 cases, nine occurred in renal, six in bone marrow, four in liver, three in heart and two in lung transplant recipients. Median time to onset was 17 months; 71% occurred within 24 months of transplantation. PML tended to occur later in the kidney recipients (P=0.04). Seventy-five percent had subacute presentation; hemiparesis (50%), apathy (46%) and confusion (38%) were the most frequently presented features. Treatment included reduction of immunosuppression and chemotherapy, mainly cidofovir. Death occurred within 2.5 months of the onset of symptoms in 17 patients (71%). PML is a unique entity that should be considered in any transplant recipient with neurological symptoms. The outcome is usually fatal, although regression has been reported.