Two AML patients, whose leukemic clonogenic cells totally reacted to the anti-lactofucopentaose III S4-7 monoclonal antibody (MoAb), underwent autologous bone marrow transplantation, in first complete remission, after in-vitro purging with S4-7 MoAb and complement. After ablative chemotherapy (BAVC regimen) and reinfusion of S4-7 purged cells, regeneration of marrow cells occurred with prompt recovery of granulopoiesis and erythropoiesis. A more delayed platelet recovery was observed. The two patients are in complete remission at 20 and 11 months from ABMT. The results indicate that immunologic purging with S4-7 MoAb is safe and suitable for selected AML patients undergoing ABMT.