Multiple factors contribute to transplant-related complications after high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation, including conditioning regimens, number of infused stem cells and clinical characteristics of patient at transplant. We compared the transplant-related complications of 141 patients affected with hematological malignancies with those of 109 patients with solid tumors. The total number of peripheral blood stem cell transplantations performed was 339. High-dose chemotherapy mainly consisted of melphalan-, busulphan- or thiotepa-based regimens. Despite the equal number of infused CD34+ cells, patients with a hematological malignancy showed a slower absolute neutrophil count (days to neutrophils > 0.5 x 10(9)/L, 10.6 +/- 3.6 for hematological malignancies versus 9.1 +/- 1.2 for solid tumors, P < 0.0001) and platelet recovery (days to platelets > 20 x 10(9)/L, 16.4 +/- 9.8 for hematological malignancies versus 12.3 +/- 4.1 for solid tumors, P < 0.0001) than patients with a solid tumor. A significantly higher requirement of red blood cell (3.3 +/- 4.1 versus 2.0 +/- 1.9, P < 0.0029) and platelet units (7.5 +/- 10.4 versus 4.2 +/- 3.4, P < 0.0001) was observed for hematological malignancies than for solid tumors. Five graft failures were documented exclusively in patients with a hematological malignancy. Moreover, such patients displayed a longer duration of mucositis (P < 0.0028) and hospital stay (P < 0.0001), but no difference was observed in terms of febrile episodes. Transplant-related mortality was similar between the two groups. In conclusion, patients with a hematological malignancy overall have more complications than those with a solid tumor.