© 2022, Edizioni Luigi Pozzi. All rights reserved.INTRODUCTION: Primary function of regulatory T(Treg) cells is to control and regulate the immune responses. In many patients with tumor tissues, increased Treg cell numbers have been reported. In this study, we aimed to measure the cellular content of blood samples in patients with gastric cancer (GC) and define their role in tumor progression. METHODS: We prospectively evaluated 34 gastric cancer cases and 20 healthy control samples. The blood was collected from both the gastric coronary and peripheral veins of the patients and only from the peripheral vein of the control group. Cellular content and lymphocyte subset including, regulatory T cells, were determined by flow cytometric analysis. RESULTS: The GC patients revealed similar percentages of T cells, B cells, neutrophils, and eosinophils in the venous samples from periphery vein and gastric coronary. The percentage of monocytes from the tumor-draining gastric coronary vein was significantly lower than monocytes from the peripheral vein in gastric cancer patients (p=0.03). T-regulatory cells had a higher percentage in samples obtained from gastric cancer patients compared with the control group. CONCLUSION: Our findings confirmed that patients with gastric cancer have a significantly higher percentage of regulatory T cells than the control group, suggesting that they may contribute to the tumor progress. Regulatory T cells and monocytes interact in patients with GC, which can be used as a parameter in the clinical follow-up of patients with GC.-ONLY COPPROHIBITE.