Rabbits were fed on cholesterol-rich (CHO) diet first for 60 days, and serum cholesterol, serum lipid peroxides (LPO) and superoxide dismutase (SOD) activities were measured at various periods after the withdrawal of the CHO-rich diet. The correlation of the above figures and the initiation, progression and regression of atherosclerotic lesion were studied. Results showed that: (1) when rabbits were fed on a CHO-rich diet for 60 days, the serum CHO and LPO increased significantly. Anyhow, the SOD activity was only slightly elevated when tiny atherosclerotic lesions developed in the aortae. (2) right after withdrawal of the CHO diet, serum CHO decreased significantly, but atherosclerotic lesion became even more severe than before. (3) after withdrawal of the CHO diet for 120 days, serum CHO, LPO content and SOD activity all returned to normal range and the atheromatous lesion became less severe except calcification and fibrosis developed in certain areas.