The correlation between preoperative nutritional parameters and postoperative complications in 440 patients with gastric cancer were analyzed. All the nutritional parameters reflected a significant deterioration as the stages of cancer progressed, and the frequency of postoperative complications was highest in patients with stage IV gastric cancer. The incidence of anastomotic leaks was increased in patients undergoing total gastrectomy with no relation to the clinical stage or nutritional status. However, there was a close relationship between nutritional status and immunocompetence, lung complications, and infection. The nutritional indices which reliably predicted preoperatively the nutritional status of cancer patients were the serum protein concentrations including the serum albumin (Alb) and prealbumin (PA). The indices predicting postoperative complications were the Alb, PA, and total lymphocyte count. These results suggest that preoperative nutritional assessment can be beneficial for the prediction of postoperative complications.