Our purpose was to evaluate the ability of recombinant human granulocyte colony-stimulating factor (r-metHuG-CSF) as an adjunct to induction chemotherapy of acute lymphoblastic leukemia (ALL) to ameliorate chemotherapy-induced neutropenia and thus allow patients to receive full doses of chemotherapy on time. Sixteen consecutive patients with adult ALL (13 de novo, three relapsed) were treated with induction chemotherapy according to the BMFT protocol and received in addition r-metHuG-CSF (200 micrograms/m2/day). Patients who were treated with the same induction chemotherapy but without G-CSF between 1982 and 1990 served as controls. Fifteen of the 16 patients achieved complete hematological remission. One patient died because of fungal septicemia. Compared with historical controls, G-CSF-treated patients had a significantly faster neutrophil recovery in phase I, resulting in neutrophil counts > 1000/microliters at day 17 vs day 26 (in median) in controls. In phase II, the onset of severe leukocytopenia (< 1500/microliters) was significantly (p = 0.01) delayed and the degree of leukocytopenia less pronounced (mean nadir 3300/microliters) in G-CSF-treated patients compared with controls (1880/microliters). The number of days of febrile neutropenia was not different in phase I. In phase II it was lower in study patients (0 vs 1.1 days), but the difference did not reach statistical significance (p = 0.09). Full doses of chemotherapy could be given on time to 11/13 (85%) G-CSF patients but to only 7/30 (23%) controls. These data indicate that (a) G-CSF can be given along with chemotherapy in induction treatment of ALL without compromising efficacy; (b) the duration of neutropenia in phase I is markedly shortened and the degree of leukocytopenia in phase II ameliorated; (c) these beneficial effects allow patients to receive full doses of chemotherapy on time.