From May 1980 to December 1989, 107 consecutive patients with non-constitutional severe aplastic anemia underwent bone marrow transplantation at our institution using cyclophosphamide and thoraco-abdominal irradiation as conditioning regimen. During the same period, 40 patients with Fanconi anemia were also grafted after a similar conditioning, giving a total series of 147 patients. With a mean follow-up of 64 months, four male patients developed a solid malignant tumor, a number that leads to an 8-year cumulative incidence rate of 22% (eg, relative risk to general population = 41, P less than .001). These results should be considered as a warning to clinicians who follow these successfully grafted long-term patients.