We evaluated the costs and the cost utility of high-dose melphalan and autologous stem cell support followed by interferon maintenance relative to conventional treatment with melphalan and prednisone, in patients less than 60 yr of age with multiple myeloma. From March 1994 to July 1997, 274 patients with newly diagnosed, symptomatic multiple myeloma were enrolled in a prospective, non-randomized, population-based, multicenter study to evaluate the treatment with high-dose melphalan and autologous blood stem cell support. Health-related quality-of-life was measured prior to treatment and during follow-up, using the EORTC QLQ-C30 questionnaire. Resource consumption was also recorded prospectively. The intensive treatment yielded a significant increase in median survival time from 44 to 62 months compared to conventionally treated patients. The corresponding gain in quality-adjusted life years (QALY) was found to be 1.2. Cost per QALY gained by the treatment with high-dose melphalan and autologous blood stem cell support was estimated at NOK 249,000 (USD 27,000).