Ocrelizumab is indicated for relapsing remitting and primary progressive multiple sclerosis (RRMS and PPMS, respectively). In an appraisal undertaken by the National Institute for Health and Care Excellence (NICE), the company Roche presented the evidence for ocrelizumab used in patients with PPMS, which came from one single randomised controlled trial (RCT) comparing ocrelizumab versus placebo. Based on results from this trial, the licensed indication was restricted to patients with early PPMS in terms of disease duration and level of disability, and with imaging features characteristic of inflammatory activity. Overall, the Evidence Review Group (ERG) found that the RCT had a low risk of bias. In the post-hoc defined magnetic resonance imaging (MRI) active subgroup, matching the label indication, the risk of confirmed disability progression sustained for 12 weeks (CDP-12) was significantly delayed in the ocrelizumab group compared to placebo. However, considering the same risk with progression sustained for 24 weeks (CDP-24), which was deemed the most clinically relevant, the benefit from ocrelizumab did not reach statistical significance. In the same MRI active subgroup, benefits from ocrelizumab on functional outcomes and on health-related quality of life were not clearly demonstrated. A de novo Markov model was used to estimate the cost-effectiveness of ocrelizumab versus best supportive care (BSC) for treating patients with PPMS. Health states were defined by the Expanded Disability Status Scale (EDSS), ranging from 0 to 9. Disability progression was based on the MSBase natural history cohort that exhibited disease progression in the absence of disease-modifying therapy. Treatment with ocrelizumab delayed disability progression, with evidence of its clinical effectiveness obtained from the RCT. The economic analysis was undertaken from the National Health Service and Personal Social Services perspective, and the outcomes were reported in terms of life years gained and quality-adjusted life years (QALYs), with the overall results reported in terms of an incremental cost-effectiveness ratio (ICER), expressed as cost per QALY gained over a 50-year time horizon. Both costs and effects were discounted at 3.5% per annum. The company undertook deterministic one-way sensitivity analyses and scenario analyses, including probabilistic sensitivity analysis (PSA). The ERG raised several concerns, which were discussed at the appraisal committee meetings, resulting in the committee's preferences being applied and a revised economic analysis from the company. Under an approved patient access scheme with appraisal committee preferences applied, analyses yielded an ICER of approximately £78,300 per QALY. Sensitivity analysis results indicated that the treatment effect on CDP-12 had the greatest impact. Results for the PSA showed that at a willingness-to-pay threshold of £30,000 per QALY gained, ocrelizumab versus BSC had a zero probability of being cost-effective. Following new analyses submitted by the company, with a revised confidential patient access scheme, NICE recommended ocrelizumab in the treatment of early PPMS in adults with imaging features characteristic of inflammatory activity.