OBJECTIVES: A single 6 mg once-per-cycle injection of pegfilgrastim was compared with daily filgrastim (mean 10.5 days/cycle) in a double-blind, randomized, multinational, phase 3 study in patients (pts) receiving 4 cycles of myelosuppressive chemotherapy. The observed incidences of febrile neutropenia (13% v 20%), hospitalization (18% v 31%), and IV anti-infective use (17% v 21%) were lower across all cycles in the pegfilgrastim arm. Pegfilgrastim was safe and well tolerated. This economic analysis was conducted to determine if pegfilgrastim would lead to a reduction in resource utilization and cost. METHODS: Duration of all-cause hospitalization, IV anti-infective use, and transfusion in each cycle and across all cycles were compared. Unit costs were available for five participating countries: Germany, Italy, the Netherlands, Spain, and the US. Each set of country specific unit costs was applied to the entire study sample, and the total cost was calculated as the sum of costs of hospitalization, IV anti-infectives, and transfusion. All costs were converted into year 2000 Euros. RESULTS: Economic analysis was performed on 152 pts (77 in pegfilgrastim arm) evaluable for efficacy (97% of all randomized pts). The mean [sd] durations of all cause hospitalizations (1.18 [3.10] v 3.77 [8.72] days) and IV anti-infective use (0.70 [2.34] v 2.32 [6.09] days) were significantly lower (p <0.05) in the pegfilgrastim arm. The total cost across all cycles in the pegfilgrastim arm was significantly lower regardless of what country costs were used (p <0.02 in all comparisons). The mean difference in Euros was 672 (Italian), 759 (Spanish), 982 (Dutch), 1068 (German), and 1836 (US). CONCLUSIONS: Compared with daily filgrastim, once-per-cycle fixed-dose pegfilgrastim led to reduced length of hospitalization and IV anti-infective use, and total cost post chemotherapy. In addition to its simplicity and convenience, pegfilgrastim appears to have superior economic value to daily filgrastim.