Abstract: Objective 　To investigate the content s of CD4 CD25 T cells and the expression of FoxP mRNA in these Treg cells in peripheral blood of the patients with gast ric cancer and to characterize their clinical significance. Methods 　By using flow cytometry, the levels of CD4 CD25 T cells in peripheral blood of 20 preoperative patient s with gastric cancer were determined. RT-PCR techniques were used to detect the expression of FoxP mRNA in these Treg cells, and the results were analyzed statistically in comparison with that of 20 healthy volunteers. Results 　The percentage of CD4 CD25 T cells in total CD4 T cells isolated f rom the patient s with gastric cancer was (12. 76 ±0. 46) %, in comparison, it was (6. 81 ±0. 66) % in those f rom healthy volunteers. It was obviously different between Treg cells amount of gastric patients and that of volunteers ( P < 0. 01) . The FoxP mRNA expression of Treg cells in the patients with gastric cancer (0. 84 ±0. 02) %〕was significantly higher than that in healthy volunteers 〔(0. 76 ±0. 03) %, ( P<0. 05) . Conclusion 　The levels of CD4 CD25 T cells in peripheral blood and the FoxP mRNA expression of Treg cells in gast ric cancer patient s were increasing significantly. FoxP genes may play a pivotal role in regulating the function of Treg cells in self-tumor immunity of the patient s with gastric cancer.