We report a right atrial myxoma which suddenly developed in a thalassemic patient after allogeneic bone marrow transplantation. The tumor was first detected by echocardiography on day +47 after transplant and the patient underwent surgical removal of the myxoma on day +103. The post-operative course was uneventful, and at more than 3 years from the event, he is alive and well, cured from his congenital disease, with no detectable intra-cardiac tumor. The onset of the myxoma in the early post-transplant period and the extremely high velocity of growth suggest a possible relationship of this condition with the immunosuppressive status.