A multicenter comparative trial of mitomycin C and futraful (MMC+FT), with or without protein-bound polysaccharide (PSK), was carried out by the Study Group for Surgical Adjuvant Chemotherapy for Gastric Cancer from 1978 to 1981. In 751 patients who underwent macroscopically curative resection preoperative granulocyte and lymphocyte count ratios (G/L) were measured. These patients were stratified with a preoperative cut-off of G/L:2.0, and those with or without PSK were compared in terms of survival rates. In the overall (non-stratified) series, the 5-year survival rate of the PSK group was 67.9%, while that of the non-PSK group was 61.8% (p=0.053). In the group with a preoperative G/L ratio of >/=2.0, the 5-year survival rate of the PSK group (n=182) was 68.7%, while that of the non-PSK group (n=182) was 55.4% (p=0.007). In the cases with a preoperative G/L ratio of <2.0, there was no significant difference in the survival rates: 67.1% in the PSK group (n=195) and 67.8% in the non-PSK group (n=192). It was found that PSK extended survival in the group of patients with a preoperative G/L ratio of >/=2.0, perhaps through restoration of immunocompetence.