Immune clinical events and pattern of recovery of total lymphocytes, T cells and CD4+/CD8+ T cell subsets, B cells and NK cells, were analysed after allogeneic blood cell transplantation (BCT) for 12 months following transplant (n = 33). Results were compared with immune recovery after allogeneic bone marrow transplantation (BMT) (n = 15) and autologous blood cell transplantation (n = 19). Rates of acute GVHD were comparable in the two allotransplantation groups. Fourteen out of 17 evaluable alloBCT group patients have presented an extensive cGVHD. Total T cell, CD4+T cells and CD56+NK cell reconstitution were improved in alloBCT group vs alloBMT group. CD4+/CD8+ ratio evolution were improved in alloBCT group vs alloBMT and autoBCT groups. These results confirm that rapid immune recovery is associated with allogeneic blood stem cell transplantation.