The neutrophil-lymphocyte ratio (NLR) reflects inflammatory status. An elevated NLR has been reported to be a prognostic indicator in some malignant tumors. The aim of this study was to evaluate the clinical significance of the preoperative NLR in patients with primary gastric cancer. A total of 709 men and 319 women, with a mean age of 64.4 years, who underwent gastrectomy were included. The numbers of patients in each pathological stage were as follows: stage I, 584; stage II, 132; stage III, 153; and stage IV, 159. The mean NLR was 2.62 +/- 1.68. A total of 127 patients (12.4%) with an NLR of 4.0 or more were classified as high NLR individuals in this study. The prognostic significance of a high NLR, together with various clinicopathological factors, was evaluated by multivariate analysis. The 5-year survival of patients with a high NLR was significantly worse than that of patients with a low NLR (57% vs 82%, P < 0.001). Univariate and multivariate analyses of clinicopathological factors affecting survival revealed that high NLR, depth of tumor, positive lymph nodes, distant metastasis, peritoneal metastasis, poorly differentiated type, and high platelet count were significant risk factors for reduced survival. On multivariate analysis, after adjusting for tumor stage, a high NLR was an independent risk factor for reduced survival (P = 0.003; adjusted hazard ratio, 1.845; 95% confidence interval, 1.236-2.747). A high preoperative NLR may be a convenient biomarker to identify patients with a poor prognosis after resection for primary gastric cancer.