To reduce the incidence of GvHD and the rate of graft failure in unrelated stem cell transplantation, we incorporate anti-thymocyte globulin in the preparative regimen in 98 patients with hematological or inherited storage disease. The median age was 32 years (range: 1-56) and 84 patients underwent transplantation from HLA-A,-B and DR identical donor, while in 14 patients the donor were mismatched either in HLA- A, -B or -DR locus. Only one patient with chronic myelocytic leukemia (CML) and blast crisis had a primary graft failure (1%). Grade II-IV acute GvHD occurred in 37 patients (37%), grade III/IV GvHD developed in 15 patients (15%). Chronic GvHD was observed in 29%, and only 12 patients had extensive GvHD (17%). After a median follow-up of 34 months (range, 9-90), the estimated overall survival at 3 years for all patients is 58% (CI 95%: 48%-68%), and the estimated disease-free survival at 3 years is 49% (CI 95%: 38%-60%). For patients with CML transplanted in first chronic phase or accelerated phase (n=40), the estimated overall survival at 3 years is 70% (CI 95%: 56%-84%), and the estimated disease-free survival at 3 years is 58% (CI 95%: 17%-85%). ATG in unrelated stem cell transplantation reduces the risk of severe acute and chronic GvHD and of graft failure without an obvious increase of severe infection. Further follow-up is mandatory to determine the incidence of late relapse.