Central nervous system (CNS) lymphoma is a rare posttransplant lymphoproliferative disorder (PTLD), which usually has a poor outcome. To date, no specific conditions predisposing to this complication have been identified. We here describe the case of a renal transplant patient who was initially diagnosed as having Epstein-Barr virus (EBV)-associated leukoencephalopathy and ultimately developed EBV-positive CNS lymphoma. The patient was a young lady who, 2 years after transplantation, presented with focal neurological and electroencephalographic abnormalities and diffuse white matter lesions on brain magnetic resonance imaging. EBV-DNA was detected in the cerebrospinal fluid (CSF) by polymerase chain reaction. After acyclovir therapy and immunosuppressive drug tapering, the symptoms and electroencephalographic abnormalities subsided, and EBV-DNA disappeared from the CSF. Ten years later, a bulky cerebral mass was found. After excision, a diagnosis of EBV-positive, Hodgkin-like monomorphic B-cell PTLD was made. This case illustrates the potential pathophysiological relationships between EBV infection, leukoencephalopathy and CNS lymphoma; although a long time elapsed from the initial neurological illness to CNS lymphoma, a link between these two conditions cannot be excluded. Therefore, a careful long-term follow-up of EBV-related encephalopathy is advisable.