We assessed the ability of granulocyte colony-stimulating factor (G-CSF) to mobilize peripheral blood stem cells (PBSC), the efficacy of PBSC infusion in the rescue of hematopoiesis after high-dose chemotherapy in 22 adult patients with hematological malignancies, and the long-term quality of engraftment. Bolus subcutaneous injections of G-CSF (12 micrograms/kg/day) were administered for 6 days. A median of three leukaphereses resulted in the collection of a median of 5.45 X 10(8) mononuclear cells/kg, 4.52 X 10(6) CD34+ cells/kg, and 3.97 X 10(4) CFU-GM/kg. G-CSF (5 micrograms/kg daily) was administered after PBSC infusion until granulocyte recovery. The median time to attain a neutrophil level > 0.5 X 10(9)/L and a platelet count > 20 X 10(9)/ L was 11 days. The median follow-up in 17 survivors was 23.8 months. These patients have maintained a complete and stable graft and some of them with neoplastic recurrence tolerated further chemotherapy. These results confirm that mobilization of PBSC by G-CSF can be performed on an outpatient setting and used in heavily pretreated patients. G-CSF mobilized PBSC transplantation provides early and complete engraftment in most patients.