The National Institute for Health and Care Excellence (NICE) invited the manufacturer of vortioxetine (Lundbeck) to submit clinical and cost-effectiveness evidence for vortioxetine for the treatment of major depressive episodes (MDEs), as part of the Institute's Single Technology Appraisal (STA) process. The Centre for Reviews and Dissemination and Centre for Health Economics at the University of York were commissioned to act as the independent Evidence Review Group (ERG). This article provides a description of the company submission, the ERG review and the resulting NICE guidance TA367 issued in November 2015. The ERG critically reviewed the evidence presented in the manufacturer's submission and identified areas requiring clarification, for which the manufacturer provided additional evidence. Two phase III randomised controlled trials for a second-line population involving vortioxetine were identified-REVIVE and TAK318. These two trials represent only 972 of over 7000 patients included in trials of vortioxetine. In REVIVE, there was a statistically significant difference in depression scores favouring vortioxetine compared with agomelatine [mean Montgomery-Åsberg Depression Rating Scale (MADRS) score difference of 2.16 points; 95 % confidence interval 0.81-3.51]. The ERG concluded that, based on all the evidence, rather than the substantially restricted subset of evidence originally considered by the manufacturer, vortioxetine is likely to be similar in efficacy to other analysed antidepressants [citalopram, sertraline, escitalopram and venlafaxine extended release (XR)], and may be more efficacious than agomelatine and inferior to duloxetine. The ERG concluded that vortioxetine may be more tolerable than other analysed antidepressants (sertraline, venlafaxine XR and bupropion), although the limited data prevent firm conclusions. The base-case incremental cost-effectiveness ratio (ICER) of vortioxetine reported by the manufacturer was £378 per quality-adjusted life-year (QALY) compared with venlafaxine. Given considerable concerns about the indirect treatment comparison undertaken by the manufacturer, the use of only a restrictive subset of the available evidence, and concerns regarding comparators and structural model assumptions, the ERG believes that this is not a valid estimate of the cost effectiveness of vortioxetine. Following corrections made to the model made by the ERG, the estimated cost effectiveness of vortioxetine was sensitive to the source of evidence used, in addition to whether certain comparators were excluded. The NICE thus asked the manufacturer to provide a revised economic model, which incorporated the broader evidence base and considered the cost effectiveness of vortioxetine as a third-line treatment. Assuming equal efficacy, vortioxetine was shown to be less costly and generate a higher QALY gain than relevant comparators at the third-line of treatment owing to its tolerability and adverse event profile. The NICE Appraisal Committee recommended vortioxetine as an option for treating MDEs in adults whose condition has responded inadequately to two antidepressants within the current episode.