The purpose of this study is to elucidate the effect of preoperative parenteral nutritional support (PNS) plus chemotherapy on tumor cell kinetics. 19 advanced gastric cancer (AGC) patients were divided into the following groups: group A (n = 7): in addition to their oral intake, received a PNS for 5 days, which yielded 117 Kj.kg-1.d-1 of non-protein calories and 0.15g.kg-1.d-1 of nitrogen. Group B(n = 6): were infused with 5-Fu at 8-10mg.kg-1.d-1 for 5 days and mitomycin C at 6-8mg.d-1 on the first and fifth day. Group C (n = 6): received a PNS plus 5-Fu with MMC as group A and B did. Specimens of gastric cancer and normal gastric mucosa were taken endoscopically before and after PNS. All specimens were studied by flow cytometry for cell cycle analysis. The results showed that the frequency of cells in S and proliferative phases were significantly increased after PNS (P0.01, P0.001), but decreased after PNS+chemotherapy (P0.05, P0.025). No significant change after single chemotherapy was observed. In conclusion, PNS might enhance the effect of chemotherapy in AGC patients, probably, by stimulation of tumor cell kinetics.