Post-transplant lymphoproliferative disorder (PTLD) in the central nervous system (CNS) is a very rare complication of haematopoietic stem cell transplant (HSCT) and has a dismal prognosis. We report the successful treatment of this disorder with intrathecal rituximab therapy in two children who developed isolated CNS PTLD after HSCT. These children had failed to respond to standard chemotherapy, intravenous rituximab and EBV specific cellular therapy. Pediatr Blood Cancer 2012; 58: 459–461. © 2011 Wiley Periodicals, Inc.