The National Institute for Health and Care Excellence (NICE) invited Servier, the company manufacturing trifluridine and tipiracil (T/T; trade name: Lonsurf(A (R))), to submit evidence for the clinical and cost effectiveness of T/T compared with best supportive care (BSC) for metastatic colorectal cancer (third-line or later). Kleijnen Systematic Reviews Ltd (KSR), in collaboration with Maastricht University Medical Center, was commissioned as the Evidence Review Group (ERG). This paper presents a summary of the company's submission (CS), the ERG report and the development of the NICE guidance for the use of this drug in England and Wales by the appraisal committee (AC). The ERG produced a critical review of the clinical and cost effectiveness of T/T based upon the CS. In the CS, pooled evidence of two trials (a phase II trial and RECOURSE) showed that T/T resulted in a significant increase in overall survival [OS; hazard ratio (HR) 0.67, 95% CI 0.58-0.78] and progression-free survival (PFS; HR 0.46, 95% CI 0.40-0.53). The AC considered the survival benefit of T/T clinically meaningful although relatively small. The ERG highlighted that none of the participants in the phase II trial and approximately half of the RECOURSE participants (394 of 800) were from Europe, which might limit the applicability of the study findings to the NHS. Moreover, the ERG's critical assessment of the company's economic evaluation highlighted a number of concerns that resulted in 11 adjustments to the company's base-case analysis. The ERG adjustments that had the largest impact were using the RECOURSE trial data only (instead of the pooled evidence), fixing errors and violations and using the utilities from the CORRECT trial (identified in the literature review) only. The ERG preferred to use the RECOURSE trial data only given the suboptimal methodology used by the company to pool the evidence. However, since there were no fundamental arguments to prevent the two trials from being pooled, the ERG also presented its base-case analysis based on the pooled effectiveness estimates. The company base-case resulted in an incremental cost effectiveness ratio (ICER) of A 44,032 pound per QALY gained while the ERG base-case resulted in ICERs of A 52,695 pound and A 49,392 pound per QALY gained based on the RECOURSE trial only and pooled evidence, respectively. Since the AC concluded that the most plausible ICER was A 49,392 pound per QALY gained, and that T/T meets end-of-life criteria, T/T was recommended as a cost effective use of NHS resources.