Short term clinical results of bone marrow transplantation on 66 patients conditioned with fractionated total body irradiation (12 Gy in 6 fractions and 3 days) are presented here. An acute toxic effects incident, similar to that obtained previously, a 27.6% interstitial pneumonitis associated with acute severe graft versus host disease in 77% of cases, 19.2% relapses, and 41% total crude survival with an actuarial probability of surviving for more than two years of 46% for ALL, 64% for AML and 28% for CML, are the results obtained since now.