66 Background: Patient-specific prognosis for gastric cancer is difficult to determine. Internationally accepted AJCC TNM staging system currently provides the best framework for predicting a patient’s prognosis. However, a major weakness of the TNM system is that significant survival differences exist even within its subgroups. The objective of this study was to create a simple tool to accurately predict patient survival from gastric cancer after gastrectomy. Methods: Between December 1986 to March 2007, 10,621 patients were surgically treated for gastric cancer at a single institution and observed until death. A nomogram was determined using Cox proportional hazard regression for multivariate analysis and the Kaplan-Meier method for estimation of 5-year overall survival. Overall survival was the endpoint. The predicted probability of the nomogram for actual overall survival was compared to the 7th edition AJCC TNM staging system. Then, the nomogram was validated using external data sets from four different institutions from Korea, Japan, and China. The number of patients in each data set was 1573 (A), 297 (B), 78 (C) and 767 patients (D). Results: Variables selected for the prediction model included age, gender, depth of invasion, number of metastatic lymph nodes (LN), total number of LN retrieved, and the presence of distant metastasis. The newly developed nomogram more accurately predicted a gastric cancer patient’s overall 5-year survival than the 7th Edition AJCC TNM system (p=0.0024) with area under the curve 0.8023 (our nomogram) and 0.7869 (AJCC TNM staging system). The concordance indexes of the different validation sets were 0.824 (A), 0.835 (B), 0.916 (C), and 0.767 (D). Conclusions: Our simple nomogram requires minimal patient and tumor information. It accurately predicts the 5-year overall survival for a patient with gastric cancer after surgical resection. Already internationally validated with data sets of various sample sizes and from different countries, our new nomogram provides a useful tool for prognostication after gastrectomy with wide applicability in different patient populations and institutions.