OBJECTIVES To evaluate the cost-effectiveness of MabThera in patients with severe GPA and MPA in the United Kingdom (UK). BACKGROUND In March 2014 NICE issued positive guidance for the use of MabThera in patients with severe GPA and MPA [TA 308]. METHODS An economic model was developed to reflect the healthcare system and the current treatment pathway in the UK. The cost-effectiveness analysis employs a Markov model with four health states: complete remission, non- remission, uncontrolled disease and death. Patients were assumed to start in the non-remission health state, transitioning based on their response to treatment. Relapsing patients who have exhausted all available treatment options they are assumed to enter the uncontrolled disease health state where they remain until death. The efficacy data for the intervention and comparator arm were taken from the RAVE study (Stone et al 2010) which demonstrated that MabThera was non-inferior to cyclophosphamide (CYC). In a subgroup of patients who had received prior therapy, MabThera was superior to CYC. Benefits were expressed as QALYs. Costs were calculated from a National Health Service and Personal Social Services perspective. The analysis calculated incremental costs and benefits associated with the addition of MabThera to the treatment paradigm which was assumed to consist of CYC and azathioprine. For patients intolerant to CYC, MabThera was assumed to substitute for CYC. The RAVE trial reports health related quality of life using SF-36. The SF-36 scores were converted to EQ-5D in a post-hoc analysis using a published model [Ara and Brazier 2008]. RESULTS Base case results estimated incremental costs of approximately £3,700 and incremental QALYs of 0.306. The incremental cost-effectiveness ratio (ICER) was £12,100 per QALY gained.  CONCLUSIONS The results of this analysis suggest that MabThera is a cost-effective treatment for severe GPA and MPA.