We compared a single, subcutaneous fixed dose of 6 mg pegfilgrastim on day +5 with daily lenograstim 263 microg from day +5 and continued until neutrophils were >or=0.5 x 10(9)/L after allogeneic peripheral blood stem-cell transplantation (PBSCT) from unrelated donors for various hematological disorders. Neutrophil engraftment was significantly faster (p = 0.006) in the pegfilgrastim than in the lenograstim group. There was also a tendency towards achieving a faster platelet engraftment (p = 0.06) in the pegfilgrastim group (median 16 vs. 19 days). The duration of thrombocytopenia (<20 x 10(9)/L) was shorter in the pegfilgrastim group (p = 0.05). There were no significant differences in the duration of neutropenia (p = 0.14) and febrile neutropenia (p = 0.25). Differences were not observed in the treatment related mortality, disease free and overall survival between both groups. We conclude that Pegfilgrastim ensured rapid neutrophil engraftment after unrelated allogeneic peripheral SCT, which was at least as effective as daily lenograstim.