Post-transplant lymphoproliferative disease (PTLD) is a rare but severe form of Epstein-Barr virus (EBV)-driven complication that develops in patients after haematopoietic stem cell transplantation. In rare cases it manifests as primary central nervous system (CNS) involvement, which is thought to be the most unfavourable localisation with respect to outcome. Disease confined to the CNS is much more challenging than systemic PTLD, and one of the contributing factors is the limited drug penetration across the blood-brain barrier. We describe the case of a 29-year-old woman who was successfully treated for PTLD with CNS involvement. The patient was diagnosed with T-cell lymphoblastic lymphoma and underwent the procedure of haematopoietic stem cell transplantation from an unrelated donor. Two months after transplantation she manifested severe headache and progressive mental deterioration accompanied by enlargement of the lymph nodes. Magnetic resonance imaging (MRI) scan revealed segmental, asymmetrical thickening of the meninges. Based on the clinical picture and the laboratory findings diagnosis of PTLD was made. The patient was effectively treated with reduction of immunosuppressive therapy and intravenous rituximab. Initially started intrathecal chemotherapy was stopped due to iatrogenic complications. We conclude that in this case the involvement of meninges in the course of the lymphoproliferative process might have compromised the blood-brain barrier. This factor probably improved rituximab's penetration to CNS, contributing to our patient's recovery.