[en] Background and Objectives. In the EORTC ALL-3 trial, the efficacy of allogeneic transplantation was compared with that of autologous marrow transplantation and maintenance chemotherapy in patients less than or equal to 50 years who reached CR. Design and Methods. Among 340 patients who entered the study, 279 were less than or equal to 50 years old. Out of these, 220 reached CR, 184 patients started consolidation and were HLA typed; 68 had a donor and 116 had no sibling donor. The median follow-up was 9.5 years; 93 patients relapsed, 26 died in CR, and overall 116 patients died. Allogeneic transplantation was performed in 47 (68%) patients with a donor while autologous transplantation or maintenance chemotherapy was given to 84 (72%) patients without a sibling donor. Results. The 6-year disease-free survival rate was similar in the groups with and without donor [38.2% (SE=5.9%) vs. 36.8% (SE=4.6%), hazard ratio 1.01, 95% CI 0.67-1.53]. Comparing the donor group with the no donor group, the former had a lower relapse incidence (38.2% vs. 56.3%, p=0.001), but a higher cumulative incidence of death in CR (23.5% vs. 6.9%, p=0.0004). The 6-year survival rates were similar [41.2% (SE=6.0%) vs. 38.8% (SE=4.6%)]. Interpretation and Conclusions. This trial did not show that allogeneic transplantation, when a sibling donor is available, produces a better outcome than the policy of offering autotransplantation or chemotherapy in the absence of a donor.