As part of the National Institute for Health and Care Excellence (NICE) single technology appraisal process, the manufacturer of crizotinib submitted evidence on the clinical and cost effectiveness of crizotinib in untreated anaplastic lymphoma kinase-positive (ALK-positive) non-small-cell lung cancer (NSCLC). Crizotinib has previously been assessed by NICE for patients with previously treated ALK-positive NSCLC (TA 296). It was not approved in this previous appraisal, but had been made available through the cancer drugs fund. As part of this new appraisal, the company included a price discount patient access scheme (PAS). The Centre for Reviews and Dissemination and Centre for Health Economics Technology Appraisal Group at the University of York was commissioned to act as the independent Evidence Review Group (ERG). This article provides a description of the company's submission and the ERG's review and summarises the resulting NICE guidance issued in August 2016. The main clinical-effectiveness data were derived from a multicentre randomised controlled trial-PROFILE 1014-that compared crizotinib with pemetrexed chemotherapy in combination with carboplatin or cisplatin in patients with untreated non-squamous ALK-positive NSCLC. In the trial, crizotinib demonstrated improvements in progression-free survival (PFS) and overall survival (OS). The company's economic model was a three-state 'area under the curve' Markov model. The base-case incremental cost-effectiveness ratio (ICER) was estimated to be greater than £50,000 per quality-adjusted life-year (QALY) gained (excluding the PAS discount). The ERG assessment of the evidence submitted by the company raised a number of concerns. In terms of the clinical evidence, the OS benefit was highly uncertain due to the cross-over permitted in the trial and the immaturity of the data; only 26% of events had occurred by the data cut-off point. In the economic modelling, the most significant concerns related to the analysis of OS and assumptions made regarding the duration of therapy. The ERG exploratory re-analysis of the OS data relaxed the assumption of proportional hazards made in the company submission, which demonstrated significant uncertainty regarding the OS gains from crizotinib. The ERG reconfigured the economic model so that duration of therapy was based on the area under the curve analysis of the PROFILE 1014 trial, dramatically increasing the cost associated with implementing crizotinib and consequently, substantially increasing the ICER. At the first appraisal meeting, the NICE Appraisal Committee concluded that crizotinib, while clinically effective, was not sufficiently cost effective for use in the UK NHS. Following the consultation, the company offered a revised PAS and conducted extensive re-analysis, resulting in a revised base-case ICER of £47,291 per QALY gained. The NICE Appraisal Committee concluded that crizotinib was likely to be a cost-effective use of NHS resources, despite the uncertainty that persisted around a number of factors, namely the long-term survival benefit of crizotinib. Crizotinib was therefore recommended as an option for untreated ALK-positive advanced NSCLC in adults.