The present study investigated the effects of CD34(+) cell selection in 102 patients using the CliniMACS device. Patients were at high risk for the development of graft versus host disease (GvHD) because of age, or the use of a haploidentical, mismatched or unrelated donor (UD). The median age of the patients was 44 years. The CliniMACS procedure yielded 8.0 x 10(6) CD34(+) cells/kg and the number of residual T cells was 1.3 x 10(4)/kg (median). The median follow up was 20.6 months. The probability of graft failure was 7%. The rate of acute GvHD was low (compatible family donors 10%, UDs 17%, and haploidentical donors 26%) with no patient enduring more than grade II disease. The cumulative incidence of chronic GvHD at the median follow up after transplant was 15% for the compatible family donor group, 40% for the UD group and 78% in the group transplanted from a haploidentical donor Treatment failure was mainly because of transplant-related mortality, especially aspergillus infection, and not due to relapse. The probability of disease-free survival, stratified for the risk of treatment failure, was 27% for the high risk, 46% for the intermediate risk and 83% for the low risk group.