Studies that have assessed the use of granulocyte colony-stimulating factor (G-CSF) following bone marrow transplantation have shown a significantly reduced time to neutrophil recovery with the use of this agent, which may translate into a reduced duration of antimicrobial therapy and hospitalisation. We performed a pharmacoeconomic study evaluating the elective use of G-CSF after bone marrow transplantation in children. 22 consecutive children who underwent bone marrow transplantation and received G-CSF 5 micrograms/kg/day were compared with 18 such children (control group) who did not receive G-CSF. Despite a significant reduction in time to recovery of the absolute neutrophil count (ANC) to > 0.5 x 10(9)/L in G-CSF recipients compared with the control group (14 days vs 20.9 days; p < 0.0001), there was only a trend towards a reduction in the duration of intravenous antimicrobial therapy (14.5 days vs 18.6 days; p = 0.15), and there was no significant difference in the duration of hospitalisation (25.3 days vs 29.8 days). Reasons for prolonged hospitalisation beyond ANC recovery included continued use of total parenteral nutrition, treatment of graft-versus-host disease and treatment of ongoing infection. Overall, the mean total cost for patients receiving G-CSF was Pounds 15001, compared with Pounds 15482 for the control group (1995 values). In conclusion, while there appears to be no benefit in financial terms, the release of a child from strict isolation as a result of early ANC recovery must be taken into consideration.