Aim To assess the effects of aspirin on early atherosclerosis. Methods 24-month-old miniature pigs were randomly assigned into three groups: control(n=6) which were fed on normal chow,3.0% cholesterol group(n=8) which were fed on atherogenic diet containing 3.0% cholesterol,aspirin group(n=8) which were added aspirin 150 mg/d in 3% cholesterol group atherogenic diet.The atherogenic diet was continued for 6 months.Half pigs for each group were killed to determine the extent of atherosclerosis and the effects of aspirin after 4 months and 6 months. Results Cholesterol feeding induced significant artery atherosclerosis by 4 months.Morphometric analysis showed the maximal intima thickness,intima area were 107.2±45.7 μm and 0.113±0.05 mm2 in 3% cholesterol group,74.2±24.7 μm and 0.093±0.05 mm2 in aspirin group in 4 months.Whereas at the end of 6 months,maximal intima thickness,ratio of intima/media thickness,intima area and ratio of intima/media area were 152.9±86.1 μm,0.85±0.49,0.188±0.207 mm2 and 0.235±0.249 in 3% cholesterol group,47.8±19.8 μm,0.33±0.09,0.017±0.012 mm2 and 0.030±0.019 in aspirin group.The intima thickness,intima area had no statistic decline in 4 months but markedly declined in 6 months in aspirin group compared with 3% cholesterol group(p<0.05 or p<0.01). Conclusion Aspirin remarkably attenuated atherosclerosis plaque.