The purpose of this study was to demonstrate the reconstitutive potential of granulocyte colony-stimulating factor (G-CSF) (filgrastim; Neupogen-primed unprocessed whole blood after myelotoxic therapy in bad-risk lymphoma. Nine patients with resistant lymphoma were treated with BAM: a BEAM regimen modified to a 72 h course consisting of BCNU 300 mg/m2 i.v. (day 1), Ara-C 3000 mg/m2 i.v. q 12 h (day 2) and melphalan 140 mg/m2 i.v. (day 3). After 5 days stimulation with G-CSF (10 micrograms/kg) 1l of blood was drawn, kept unprocessed for 3 days and reinfused 24 h after completion of chemotherapy. Back-up peripheral stem cells were available for all patients. The neutrophil count reached 0.5 x 10(9)/l at a median of 16 days (range 11-25) and a platelet count of 10 x 10(9)/l was reached at a median of 20 days (range 11-NR (not reached)). The median length of hospital stay was short in these patients with a median of 19 days (range 17-33). In three patients platelet transfusion independence did not occur before day 28. Those patients received their back-up stem cells. Antibiotics had to be used in two patients. The median number of reinfused CD34+ cells was 0.28 x 10(6)/kg (range 0.01-0.59). When more than 0.2 x 10(6)/kg CD34+ cells were reinfused the time to recovery was comparable to that observed after 'classical PBSCT'. In conclusion, the use of G-CSF-stimulated unprocessed whole blood is easy to perform and a cheap technique to mobilize and collect stem cells that can serve as a stem cell source after severe myelotoxic therapy in bad-risk malignant lymphoma.