OBJECTIVES: to retrospectively assess the cost of treatment following reinfusion of PBPC after high-dose chemotherapy in n-HFL patients until day 90 post-reinfusion in an open-label, randomised phase III trial comparing the treatment with and without filgrastim. The study was a multi-centre trial conducted in France between 1995-1999. METHODS: Of fifty-one patients enrolled, 27 received filgrastim (FI) and 24 were in the control arm (C). Demographic and disease-specific information was collected through the CRF. Costs measured were hospital duration (normal ward and ICU), drugs, transfusions, diagnostics and lab tests. Drug prices were retrieved from VIDAL 2000 database and on-line BIAM database. Costs of hospitalization and technical procedures were obtained from one participating centre. Costs were evaluated for the first hospitalization period post-transplant (FP) and for the total duration of the follow-up period (OP). All prices are expressed in FRF 2000 currency. Due to the small sample size non-parametric rank testing was used to determine whether significant differences existed (p < .05, two –sided). RESULTS: Average FP cost per patient was 245,603.4 FRF (SD 92,950.1) for C and 218,131.8 FRF for FI (SD: 61,711.7). Cost difference was 27,352.9 FRF (11%) in favor of the filgrastim arm (p = .15). Average OP cost per patient was 267,784.9 FRF for C and 244,974.6 FRF for FI. The cost difference did not change during follow-up. Main cost drivers were, as expected, the cost of hospitalization and of IV antibiotic drugs. On average, FI patients leave the ICU 2.8 days earlier than P patients during FP. CONCLUSION: Use of filgrastim 24 hours post-PBPC following high dose chemotherapy for n-HFL patients could result in important cost reductions, mainly attributable to a shorter hospitalization in ICU and a lower use of IV-antibiotics.