Abstract: Objective:To determine the level of infiltrating macrophages in gastric cancer (GC) and to analyze the rela -tionship between macrophage infiltration and clinicopathologic features and prognosis. Methods:Immunohistochemistry was adopted to detect the level of infiltrating macrophages in37specimens of GC collected from our hospital. The number of infiltrating macrophages at the tumor-stroma interface was directly counted under the microscope. The relationship be-tween the level of infiltrating macrophages and clinicopathologic features was analyzed. Moreover, we focused on the val -ue of infiltrating macrophages in survival status of GC patients. Results: The interface of tumor nest and stroma was the main location of infiltrating macrophages in GC, as well as the areas rich in vascular formation. The area of basement mem-brane destruction was the hot region of infiltrating macrophages. The mean macrophage counts under high power field for 37GC patients and29cases without distant metastasis were 19.7 ± 8.9 and 18.9 ± 8.3, respectively. Infiltrating macrophages were not associated with age, pathological types, recurrence, or lymph node status (P>0.05). Macrophage infiltration levels were 21.6 ± 8.0 in cases with serosa-invasion and 12.7 ± 9.2 in those without serosa-invasion ( P=0.011 ). Macrophage infiltra -tion level was significantly higher in advanced GC (22.6 ± 8.1) than in early GC ( 12.8 ± 7.1) (P=0.001 ). The median survival for all 37GC patients was19.0 months and was correlated with serosa invasion, distant metastasis and TNM stage (P val-ues were 0.024 , 0.021 and 0.009 , respectively). The median disease-free survival was 13.0 months and was correlated with serosa invasion ( P=0.038 ) and TNM stage ( P=0.006 ). The cumulative overall survival was higher in the low macrophage density group ( 40.5 months) than in the high macrophage density group (13.0 months), with no significant difference (P=0.056 ). The cumulative disease-free survival (DFS) was significantly higher in the low macrophage density group ( 37.0 months) than in the high macrophage density group (9.5 months) (P=0.041 ). Conclusion:Macrophage infiltration plays a sig-nificant role in GC progression and can be used for the evaluation of prognosis. More infiltrating macrophages in tumor specimens may indicate faster tumor progression and shorter disease-free survival.