Aim The purpose of the study was to observe the expression change of AnnexinⅡ and the correlationship between the expression levels of AnnexinⅡ and the ratio of intracellular total cholesterol (TC) to cholesterol ester(CE) and to explore the significance of AnnexinⅡ in the formation of foam cells induced by ox-LDL. Methods RAW264.7 monocyte cell lines with a 90% confluency were exposed to ox-LDL (50, 100 and 200 mg/L) and native LDL(n-LDL, 200 mg/L) for 24 h, respectively, and the following parameters such as TC, CE, the release of LDH, cell viability and expression levels of AnnexinⅡwere detected by colorimetry,Western blot and RT-PCR etc. Results Our data showed that the release of LDH and cell viability in exposure to ox-LDL (200 mg/L) for 24 h were increased and decreased significantly and there were statistically significant differences (P＜0.01) compared with the n-LDL (200 mg/L) group. However, the release of LDH and cell viability in exposure to 50 mg/L and 100 mg/L of ox-LDL had no remarkable changes (P＞0.05). Moreover, the ratio of CE/TC were 55.0%±6.7%, 61.8%±4.8% and 59.6%±5.2%, respectively exposed to ox-LDL (50, 100 and 200 mg/L) and there were significant differences compared with n-LDL (200 mg/L) (P＜0.05), and peaked at the 100 mg/L of ox-LDL. In addition, further results showed that ox-LDL inhibited the expression of AnnexinⅡmRNA and protein in a concentration-dependence manner and the expression levels of AnnexinⅡ mRNA and protein were negatively correlated with the ratio of CE/TC(r₁=-0.9374, P＜0.05； r₂=-0.9548, P＜0.05). ConclusionOx-LDL inhibited the expression of AnnexinⅡmRNA and protein in a concentration-dependent manner, which suggested that it may affect the intracellular cholesterol self balance and induce the formation of foam cells.