Purpose: In Korea, the entire population must enroll in the national health insurance system, and those who are classified as having a lower socioeconomic status are supported by the medical aid system. The aim of this study was to evaluate the association of the medical insurance status of gastric cancer patients with their survival after gastrectomy. Materials and Methods: A total of 247 patients who underwent surgical treatment for gastric cancer between January 1999 and December 2010 at the Seoul Medical Center were evaluated. Based on their medical insurance status, the patients were classified into two groups: the national health insurance registered group (n=183), and the medical aid covered group (n=64). The survival rates were calculated using the Kaplan-Meier method. Results: The median postoperative duration of hospitalization was longer in the medical aid covered group and postoperative morbidity and mortality were higher in the medical aid group than in the national health insurance registered group (P<0.05). The overall 5-year survival rate was 43.9% in the medical aid covered group and 64.3% in the national health insurance registered group (P=0.001). Conclusions: The medical insurance status reflects the socioeconomic status of a patient and can influence the overall survival of gastric cancer patients. A more sophisticated analysis of the difference in the survival time between gastric cancer patients based on their socioeconomic status is necessary.