Sixty-four untreated adult acute lymphoblastic leukemia (ALL) patients were randomized to receive chemotherapy alone, n = 31 or chemotherapy and granulocyte colony stimulating factor (G-CSF), n = 33. During induction patients received G-CSF for 5 days between four weekly Epirubicin+Vcr administrations, starting 36 h after each application and finishing 48 h before the next one with the intention to possibly generate a cell cycle dependent protection of normal hematopoietic progenitors and to stimulate granulopoiesis. The complete remission (CR) rate equaled 94% in the G-CSF group and 87% in controls. Patients who received G-CSF, if compared to the controls, had shorter granulocytopenia during induction and consolidation, displayed a lower infection rate, completed the induction-consolidation quicker and stayed shorter in hospital during induction, p < 0.001-0.04. Follow-up at 2 years revealed a rather higher probability of survival (59 vs. 27%, p = 0.04) and a lower relapse rate (32 vs. 60%) in G-CSF arm than in controls. The beneficial influence of G-CSF administered in time-sequenced fashion on survival needs further confirmation.