Fourteen patients with relapsed Hodgkin's disease responded to a salvage therapy with Dexa-BEAM (dexamethasone, BCNU, etoposide, Ara-C and melphalan). In seven patients a continuous i.v. infusion with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was started subsequent to Dexa-BEAM (+rhGM-CSF) while the other seven patients received no hemopoietic growth factor (-rhGM-CSF). It was our objective to study the impact of rhGM-CSF on the collection of blood-derived hemopoietic stem cells in patients with extensive prior chemo- and radiotherapy not eligible for marrow harvest. Compared to baseline, we observed a significant increase of colony-forming units granulocyte-macrophage (CFU-GM) in the peripheral blood of patients receiving rhGM-CSF (p less than 0.05). On average, the yield of total nucleated cells and CFU-GM collected per single leukapheresis was 2.2 and 2.4-fold higher in the rhGM-CSF-treated patients respectively (p less than 0.05). With rhGM-CSF the interval from the start of chemotherapy to the end of blood stem cell collection could be reduced by 6 days (p less than 0.05). Following the CBV pretransplant regimen (cyclophosphamide, BCNU, etoposide), the reinfusion of rhGM-CSF-exposed stem cells resulted in a shorter time of leukocyte recovery (p less than 0.05). The number of CFU-GM/kg body weight transplanted was found to be predictive for the time of neutrophil recovery (p less than 0.05). In patients with bone marrow hypoplasia or fibrosis, rhGM-CSF as part of an effective salvage therapy improves the collection of blood stem cells that are capable of restoring hemopoiesis after high-dose pretransplant therapy.