A 14-year-old male and a maternally related cousin were diagnosed with X-linked lymphoproliferative disease (XLP) after developing recurrent B-NHL, characterized by long disease-free intervals and absence of an increased chemoresistance of the recurrent lymphomas. The demonstration of different clonal IgH gene rearrangements in two of the lymphomas from one of the patients further supports that the lymphomas were clonally unrelated. The cousin underwent matched related BMT, whereas the proband received a deliberately delayed MUD BMT in third CR. Both are in CR 68 months and 21 months, respectively, post-BMT. Delaying BMT probably contributes to reducing treatment-related morbidity. We suggest MUD BMT as a feasible curative strategy for XLP patients with B-NHL lacking matched related donors.