This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of certolizumab pegol (CZP) for adults with active rheumatoid arthritis (RA) that have not responded adequately to treatment with conventional disease modifying anti-rheumatic drugs (DMARDs) including methotrexate (MTX), in accordance with the licensed indication, based upon the evidence submission from the manufacturer to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal (STA) process. The outcome measures included American College of Rheumatology (ACR) 20, 50 and 70 response rates and quality of life measures after 3 months and 6 months of treatment. The ERG examined the submission's search strategies and considered they appeared comprehensive and that it was unlikely that relevant studies would have been missed. Only English language studies were considered in the submission and non-English language studies relevant to the decision problem may possibly have been ignored. The ERG analysed the first submitted economic model so as to itemise in detail clarification points that were brought to the attention of the manufacturer. In response the manufacturer submitted a modified cost-effectiveness analysis. The ERG undertook further analysis of this second model and other additional submitted evidence. The clinical evidence was derived from two multicentre blinded randomised controlled trials (RCTs) comparing CZP + MTX to placebo + MTX (the RAPID 1 and RAPID 2 trials). RAPID 1 lasted 52 weeks with 982 patients and RAPID 2 24 weeks with 619 patients. Evidence for clinical effectiveness of CZP in mono-therapy came from the 24-week FAST4WARD trial with 220 patients that compared CZP (400 mg every 4 weeks) versus placebo. The three key RCTs demonstrated statistically significant superiority of CZP + MTX versus placebo + MTX and of CZP versus placebo with respect to a variety of outcomes including ACR 20, ACR 50 and ACR 70 measures and quality of life measures at 3 and 6 months. On the basis of results from the indirect comparison meta-analyses, the manufacturer suggested that CZP may be at least as effective as other 'biological' DMARD (bDMARD) comparators and, in a few ACR measures at 3 and 6 months, more effective. CZP is an effective therapy for adult RA patients whose disease has failed to respond adequately to cDMARDs including MTX or who are intolerant of MTX. The cost-effectiveness of CZP relative to other bDMARDs is unclear because the economic modelling undertaken may have ignored relevant effectiveness data and potential differences between trial populations, and so may have included effectiveness results that were biased in favour of CZP; underestimated uncertainty in the relative effectiveness of compared DMARDs; and ignored the potential influence of differences between bDMARDs with regard to adverse events and their related costs and health impacts. The NICE guidance issued in October 2009 states that: the Committee is minded not to recommend certolizumab pegol as a treatment option for people with RA; and the Committee recommends that NICE asks the manufacturer of CZP for more information on the clinical effectiveness and cost-effectiveness of CZP for the treatment of people with RA. On receipt of this information and details of a patient access scheme NICE issued final guidance recommending CZP, under certain criteria, as a treatment option for people with RA.