In this retrospective study, 23 recipients of peripheral blood progenitor cells (PBPC) were compared to 23 recipients of bone marrow (BM). The donors were 12 HLA-A-B-DR identical siblings and 11 HLA-A-B-DR identical unrelated donors in the PBPC and BM groups, respectively. Diagnoses in the PBPC group were CML seven, AML, nine, ALL three, lymphoma one, myeloma two and aspartylglucosaminuria (AGU) one. The median age was 40 (5-55) years. The BM group was matched for diagnosis, age, conditioning therapy, GVHD prophylaxis and G-CSF treatment after BMT. A higher number of MNC (P<0.001), CD34+ (P = 0.05), CD3+ (P<0.001) and CD56+ (P<0.001) cells in the graft, a reduced number of platelet transfusions (P = 0.03) and a significant hastening of neutrophil and platelet recovery were seen in the PBPC group compared to the BM group. In logistic regression analysis, the following factors were important for engraftment of ANC >0.5 x 10(9)/l: peripheral blood progenitor cell transplantation (PBPCT) (P = 0.003) and mononuclear cells (MNC) > or =2.5 x 10(8)/kg recipient in the graft (above median) (P = 0.009) in univariate analysis. For recovery of platelets >30 x 10(9)/l: PBPCT (P = 0.03) and HLA-identical sibling donors (P = 0.05) were significant in multivariate analysis. A trend towards a lower incidence of bacteremia was seen in the PBPC group, ie 22 vs 48% (P = 0.06) in the BM group. GVHD, TRM and survival did not differ between the two groups.