Thirty-four adults with refractory acute lymphocytic leukemia received salvage therapy with mitoxantrone 5 mg/m2 intravenously over 1 hour daily for 5 days and cytosine arabinoside (ara-C) 3 g/m2 intravenously over 2 hours every 12 hours for six doses, followed by granulocyte-macrophage colony-stimulating factor (GM-CSF) 125 microgram/m2 intravenously over 4 hours daily until recovery of granulocytes above 2.0 x 10(3)/microL. Their outcome was compared with 29 prognostically similar historical control patients treated with the identical chemotherapy without GM-CSF. Overall, the complete response rates were similar in the treatment and control groups (13 of 34 [38%] v 11 of 29 [38%]). There was a trend for less remission induction mortality in the GM-CSF-treated patients (2 of 34 [6%] v 6 of 29 [21%]; P = .08), but, conversely, a higher rate of resistant disease (19 of 34 [56%] v 10 of 29 [34%]; P = .09). Recovery of granulocyte counts above 500/microL was significantly faster in the GM-CSF-treated group (25 days v 33 days; P less than .01), but there was no reduction in the incidence of febrile episodes (91% v 93%) or of documented infections (59% v 59%). Survival was prolonged in the GM-CSF-treated patients but was not of clinical relevance (31 v 20 weeks; P = .05). In summary, the addition of GM-CSF to intensive chemotherapy in refractory adult ALL was associated with a reduction in the remission induction mortality, probably secondary to a shorter duration of granulocytopenia, but not with an improvement in complete response rates.