In December 1997, we conducted a nationwide survey of cases of primary allogeneic peripheral blood stem cell transplantation (allo-PBSCT) performed in Japan between December 1994 and November 1997 Data was collected on 103 patients with hematologic malignancies, aplastic anemia, or solid tumors. Eighty-seven patients received transplants from HLA-identical siblings, and 16 from HLA-mismatched related donors. Granulocyte-colony stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSC) were collected from donors by 1 to 3 aphereses. Apheresis products contained a median 5.4 (1.0-30.4) x 10(6) CD34 + cells/kg. Most patients were given cyclosporine and methotrexate for graft-versus-host disease (GVHD) prophylaxis. Median days to ANC > 500/microliter and platelets > 50,000/microliter were 13 (7-49) and 16 (10-94), respectively. Grade II-IV acute GVHD developed in 37/99 (37.4%) and chronic GVHD in 59/86 (68.6%) patients. The incidence of treatment-related mortality within 100 days after transplant was 16.1%. Fifty-five patients (59.6%) were alive after a median follow-up of 794 days. More patients and longer follow-up periods will be required to assess the efficacy of allo-PBSCT and evaluate graft-versus-leukemia effect along with the incidence of acute and chronic GVHD.