This study was conducted to identify dietary factors that may affect the occurrence of gastric cancer in Koreans. Preoperative daily nutrition intake and diet quality of patients diagnosed with gastric cancer were evaluated. Collected data were comparatively analyzed by gender. The results were then used to prepare basic materials to aid in the creation of a desirable postoperative nutrition management program. The subjects of this study were 812 patients (562 men and 250 women) who were diagnosed with gastric cancer and admitted for surgery at Soonchunhyang University Hospital between January 2003 and December 2010. Nutrition intake and diet quality were evaluated by the 24-hr recall method, the nutrient adequacy ratio, mean adequacy ratio (MAR), nutrient density (ND), index of nutritional quality (INQ), dietary variety score (DVS), and dietary diversity score (DDS). The rate of skipping meals and eating fast, alcohol consumption, and smoking were significantly higher in males than those in females. The levels of energy, protein, fat, carbohydrate, phosphorous, sodium, potassium, vitamin B₁, vitamin B₂, niacin, and cholesterol consumption were significantly higher in males than those in females. Intake of fiber, zinc, vitamin A, retinol, carotene, folic acid were significantly higher in females than those in males. MAR in males was significantly higher (0.83) than that in females (0.79). INQ values were higher in females for zinc, vitamin A, vitamin B₂, vitamin B₆, and folic acid than those in males. The average DVS was 17.63 for females and 13.19 for males. The average DDS was 3.68 and the male's average score was 3.44, whereas the female's average score was 3.92. In conclusion, males had more dietary habit problems and poor nutritional balance than those of females. Our findings suggest that proper nutritional management and adequate dietary education for the primary prevention of gastric cancer should be emphasized in men.