The immunocompetence and nutritional state of patients with advanced or recurrent gastric cancer is low, making it important to conduct chemotherapy while at the same time improving or maintaining their immunocompetence and nutritional state. To reduce the side effects but not the antitumor effect of TS-1, a 2-week regime of TS-1, and 1-week drug-free interval, in combination with the immunotherapeutic agent lentinan (LNT) was started in 5 patients with advanced or recurrent gastric cancer. Toxicity, efficacy, immunocompetence and nutritional state were investigated preliminarily to examine whether or not usefulness of lentinan could be evaluated. The IAP tended to decrease. TS-1 and lentinan combination immunochemotherapy was able to be carried out safely in patients with advanced recurrent gastric cancer. In order to examine the usefulness of combined LNT, it is thought to be necessary to perform a randomized trial using toxicity and not only efficacy but QOL and immunological and nutritional parameters as indicators.