Adjuvant transfusion of donor lymphocytes (aDLT) may reduce the risk of relapse after allogeneic stem cell transplantation in high-risk AML. We performed a retrospective analysis on the safety and efficacy of aDLT in a cohort of 46 patients. To be eligible for aDLT, patients had to be in CR for at least 120 days from transplantation, off immunosuppression for ⩾30 days and free of GvHD. Thirty-four patients with similar disease characteristics and fulfilling the same selection criteria served as controls. Median follow-up among aDLT recipients was 7.2 years. Ten patients (22%) relapsed inspite of aDLT, as compared with 53% in the control group. Induction of GvHD was the main complication. However, non-relapse mortality was low with patients dying from infection (n=2), severe chronic GvHD (n=1) and secondary malignancy (n=2). At the time of analysis, 31/46 aDLT recipients were alive in CR at a median of 5.7 years after first aDLT. Overall survival at 7 years after transplant was 67% as compared with 31% in the control group (P<0.001). In conclusion, aDLT is safe, when given in escalating doses to a well predefined group of patients. Long-term survival can be achieved.