This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of bortezomib for the treatment of multiple myeloma patients at first relapse and beyond, in accordance with the licensed indication, based upon the evidence submission from Ortho Biotech to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The outcomes stated in the manufacturer's definition of the decision problem were time to disease progression, response rate, survival and quality of life. The literature searches for clinical and cost-effectiveness studies were adequate and the one randomised controlled trial (RCT) included was of reasonable quality. Results from the RCT suggest that bortezomib increases survival and time to disease progression compared with high-dose dexamethasone (HDD) in multiple myeloma patients who have had a relapse after one to three treatments. Cost-effectiveness analysis based on the same trial and an observational study was reasonable and gave an estimated cost per life-year gained of 30,750 pounds, which ranged from 27,957 pounds to 36,747 pounds on sensitivity analysis. An attempt was made to replicate the results of the manufacturer's model and to compare the results to the Kaplan-Meier survival curve presented in the manufacturer's submission. In addition, a one-way sensitivity analysis and a probabilistic sensitivity analysis were undertaken, as well as additional scenario analyses. Based on these analyses the ERG suggests that the cost-effectiveness results presented in the manufacturer's submission may underestimate the cost per life-year gained for bortezomib therapy (versus high-dose dexamethasone) when potential UK practice and scenarios are considered. The guidance issued by NICE in June 2006 as a result of the STA states that bortezomib monotherapy for the treatment of relapsed multiple myeloma is clinically effective compared with HDD but has not been shown to be cost-effective and is not recommended for the treatment of progressive multiple myeloma in patients who have received at least one previous therapy and who have undergone, or are unsuitable for, bone marrow transplantation.