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Increasing studies were performed to explore the prognostic value of snail in lung cancer (LC), however, with inconsistent results. Hence, this systematic review is aimed to evaluate the prognostic role of snail in patients with LC.A comprehensive literature search in the PubMed, Embase, the Cochrane Library, and Web of Science databases will be conducted to identify eligible studies. Language is limited as English. We will employ hazard ratios (HRs) and 95% confidence intervals (95% CIs) to estimate the correlations between snail expression and overall survival (OS), progression-free survival (PFS), recurrence-free survival (RFS), disease-free survival (DFS), and clinicopathological features. Meta-analysis will be performed using STATA 14.0 software.This study will provide a high-quality synthesis of current evidence of the correlations between snail expression and OS, PFS/RFS/DFS, and clinicopathological features.The study will provide updated evidence to assess whether the expression of snail is in association with poor prognosis in patients with LC.It is not necessary for ethical approval because individuals cannot be identified. The protocol will be disseminated in a peer-reviewed journal or presented at a relevant conference.This systematic review protocol has been registered in the PROSPERO network (No. CRD42018095191).