Considerable morbidity, mortality, and economic costs result during remission induction therapy for elderly patients with acute myeloid leukemia (AML). In this study, the economic costs of adjunct granulocyte colony stimulating factor (G-CSF) are estimated for AML patients > 55 years of age who received induction chemotherapy on a recently completed Southwest Oncology Group study (SWOG). Clinical data were based on Phase III trial information from 207 AML patients who were randomized to receive either placebo or G-CSF post-induction therapy. Analyses were conducted using a decision analytic model with the primary source of clinical event probabilities based on in-hospital care with or without an active infection requiring intravenous antibiotics. Estimates of average daily costs of care with and without an infection were imputed from a previously reported economic model of a similar population. When compared to AML patients who received placebo, patients who received G-CSF had significantly fewer days on intravenous antibiotics (median 22 vs. 26, p = 0.05), whereas overall duration of hospitalization did not differ (median 29 days). The median cost per day with an active infection that required intravenous antibiotics was estimated to be $1742, whereas the median cost per day without an active infection was estimated to be $1467. Overall, costs were $49,693 for the placebo group and $50,593 for the G-CSF patients. G-CSF during induction chemotherapy for elderly patients with AML had some clinical benefits, but it did not reduce the duration of hospitalization, prolong survival, or reduce the overall cost of supportive care. Whether the benefits of G-CSF therapy justify its use in individual patients with acute leukemia for the present remains a matter of clinical judgment.