Aim To study the role of caveolae and caveolin 1 on atherosclerosis formation in scavenger receptor A_Ⅰ (SR A_Ⅰ) transgenic mice. Methods Wild type and SR A_Ⅰ transgenic mice were randomly divided into control, transgenic, wild type plus high cholesterol diet, and transgenic plus high cholesterol diet groups, fed with normal or high cholesterol diet respectively. Animals were sacrificed after 24 weeks. The area of plaque was measured by electronic computer for image analysis. Immunohistochemical analysis and electron microscopy were used to investigate the expression of caveolae and caveolin 1. Results The atherosclerotic plaque were observed in wild type plus high cholesterol diet group, transgenic group, transgenic plus high cholesterol diet group. The thickness of intima and media were thinner in normal control group than in other three groups (p<0.05). Immunohistochemical analysis showed the caveolin 1 expression in above three groups were lower than that in control group. Furthermore, electron microscopy showed the expression of caveolae were also decreased. Conclusion Decreased expression of caveolae and caveolin 1 is associated with the atherosclerosis formation in SR A_Ⅰ transgenic mice.