We analysed 99 courses of leukapheresis after the use of cytotoxic drugs or cytotoxic drugs plus G-CSF (cytotoxic/G-CSF) to mobilize peripheral blood stem cells (PBSC) in 68 patients with hematologic or solid malignancies. Mean yields of granulocyte-macrophage progenitor cells (CFU-GM) with cytotoxic/G-CSF mobilization were significantly higher than those with cytotoxic mobilization (18.6 vs 8.40 x 10(4)/kg). The optimal timing of collection was different between these two mobilizations; the mean number of days to a peak level of circulating CFU-GM after cytotoxic/G-CSF mobilization was less than that after cytotoxic mobilization (24.2 vs 27.7 days). The leukocyte level on the day of peak CFU-GM was significantly higher in cytotoxic/G-CSF mobilization than that in cytotoxic mobilization (mean 12.8 vs 2.7 x 10(9)/l), whereas the platelet level was not different (mean 132 vs 125 x 10(9)/l). Increasing patient age was not a major adverse factor for PBSC collection. Synchronous recovery of both leukocytes and platelets was critical for achieving a high CFU-GM yield in these two mobilizations. Following PBSC autotransplantation, the rate of trilineage hematologic reconstitution showed a significant correlation with the infused dose of CFU-GM, whether they were collected with cytotoxic or cytotoxic/G-CSF mobilization. These results suggest that G-CSF can expand the PBSC pool and that CFU-GM yield after cytotoxic/G-CSF mobilization may predict trilineage hemopoietic reconstitution after ABSCT, as well as cytotoxic mobilization.