The effects of autologous cytokine-induced killer (CIK) (CD3+CD56+) cells together with chemotherapy were investigated in patients who suffered from advanced gastric cancers (stage IV). Fifty-seven patients were divided into two groups: chemotherapy plus CIK biotherapy and chemotherapy alone. CIK cells were induced from autologous peripheral blood mononuclear cells in vitro and separated by flow cytometry and then transfused into the patients. The T-lymphocyte subgroups (CD3+, CD4+ or CD8+), CIK cells and NK cells (CD3-CD56+) were separated and determined by flow cytometry and the serum levels of MG7-Ag, CA72-4, CA19-9 and CEA were determined by ELISA or ECLIA. It was demonstrated that the cytotoxic activity of CIK cells reached a maximum between days 14 to 21 (68.7+/-10.9% and 65.3+/-10.4%, respectively). The amounts of CIK cells were gradually increased from day 0 to day 21 and slightly decreased in the further incubations. Thereafter, the CIK cells on days 14 to 21 (with the highest population of CIK cells) transfused back to the patients. The serum levels of the tumor markers were significantly decreased, the host immune function was increased and the short-term curative effect as well as the quality of life (QOL) were improved in the patients treated by chemotherapy plus CIK cells compared to the patients treated by chemotherapy alone. Moreover, the 2-year life-span was prolonged in the group treated by chemotherapy plus CIK cells compared to the group treated with chemotherapy alone. It is concluded that chemotherapy plus CIK cells has obvious benefits for patients who suffer from advanced gastric cancers.