Based on randomized studies bone-marrow supported (BMS) high-dose chemotherapy (HDCT) is not superior to conventional CT as adjuvant treatment for high-risk breast cancer. To compare the cost-effectiveness of these treatments we examined the data of Finnish patients in the SBG9401 trial 1. Patients were randomized to receive either dose-escalated (de FEC) (group A, n =59) or FEC and HDCT+BMS (group B, n =70). They received adjuvant radiotherapy (RT) + tamoxifen. All direct health care costs of first line treatment at the oncology units were considered as well as productivity costs within the first 3 years of follow-up. Effectiveness was measured by the number of survival days during 5 years of follow-up. The mean direct health care costs were significantly higher in group B (25829 euro in group A vs. 36605 euro in group B, p <0.001), mainly due to a higher number of hospital days. Half of the costs in group A was due to the use of filgrastim (15335 euro in A and 2969 euro in B, p <0.001). The costs of RT were only 5% of total costs. There was no statistically significant difference between the groups in the number of survival days, but sensitivity analysis based on bootstrapping suggested that treatment A would be a less costly and more effective alternative in a great majority of cases.