Macrophages are a diverse phenotype that has important functions in inherent and adaptive immunity. Macrophage ac-tivation has two distinct states of polarization:the classically activated (M1) and the alternatively activated (M2) macrophage pheno-types in different micro-environments. M2 macrophages exert an immuno-regulatory activity that is associated with the induction of Th2 responses. The macrophages can infiltrate in the tumor micro-environment, and is also known as tumor-associated macrophages (TAMs). TAMs show the M2 macrophage phenotypes that have been associated with tumor neo-vascularization, infiltration, and metas-tasis. This review aims to investigate the importance of the immuno-regulatory activity of TAM in the carcinogenesis of gastric cancers.