The prognostic role of neutrophil to lymphocyte ratio (NLR) in gastric cancer remains controversial. We aimed to quantify the prognostic role of peripheral blood NLR in gastric cancer. A literature search was conducted in PubMed, EMBASE, and Cochrane databases. The results for overall survival (OS) and progression-free survival (PFS)/disease-free survival (DFS) are expressed as hazard ratios (HRs) with 95% confidence intervals (CIs). 19 studies with 5431 patients were eligible for final analysis. Elevated NLRs were associated with a significantly poor outcome for OS (HR = 1.98; 95% CI: 1.75–2.24, p<0.001) and PFS (HR = 1.58; 95% CI: 1.32–1.88, p<0.001) compared with patients who had normal NLRs. The NLR was higher for patients with late-stage compared with early-stage gastric cancer (OR = 2.76; 95% CI: 1.36–5.61, p=0.005). NLR lost its predictive role for patients with stage IV gastric cancer who received palliative surgery (HR = 1.73; 95% CI: 0.85–3.54, p=0.13). Our results also indicated that prognoses might be influenced by the NLR cutoff values. In conclusion, elevated pretreatment NLRs are associated with poor outcome for patients with gastric cancer. The ability to use the NLR to evaluate the status of patients may be used in the future for personalized cancer care.