High-dose chemotherapy (HDC) with autologous peripheral blood stem cell (PBSC) support is a common but expensive treatment for various hematological malignancies. A prospective cost analysis of evaluation/mobilization and the HDC + PBSC phase for patients with multiple myeloma was performed. Eleven consecutive patients at the National University Hospital Oslo, taking part in a Nordic treatment protocol, were included in the analysis during the period from May 1999 to December 2000. Clinical and resource use data were obtained prospectively on a daily basis registration and from patient records. The total cost for the evaluation/mobilization and the HDC + PBSC phase varied from 22,999 US dollars to 61,722 US dollars (mean 38,186 US dollars; median 30,569 US dollars). The mean length of hospital stay for the evaluation/mobilization phase was 8 days (range 4-17 days) and for the HDC + PBSC phase 19 days (range 14-29 days). A statistically significant correlation was found between the length of hospital stay and hospital costs for both phases (P < 0.003 and P < 0.010, respectively). A large part of the actual cost in the harvest phase was attributed to stem cell mobilization, including growth factors, harvesting and cryopreservation. In the HDC + PBSC phase, the most important part of the cost was paying nursing care personnel.