Our study aimed to investigate the effects of interleukin-4 (IL-4) on macrophage polarization, as well as its role in the development of atherosclerosis. Human peripheral blood mononuclear cells (PBMCs) were isolated and randomly divided into 3 groups: control group, ox-LDL group, and ox-LDL + IL-4 groups. The expression of M1/M2 macrophage surface markers such as TNF-α, CD68, and CD206 were analyzed by western blot. Cell viability was determined using the MTT assay. Measurement of CD86/CD206 expression ratio (M1/M2 ratio) was performed via flow cytometry.