To look for the effective method of prevention and treatment for the atherosclerosis (As), we made this experiment with fatty acid sodium of evening primrose oil for observing the effect of the drug to As in morphology.Methods Sixteen rabbits were divided into one experimental and two control group. In the experimental group, 4. 1 g/kg fatty acid sodium of evening primrose oil was given to each rabbit daily for 150 days. Each rabbit of the experimental and the first control group was fed with 0. 5 g cholesterol per day. After 150 days of feeding, all the rabbits were killed by air embolism. Aorta was investigated by optics and electron microscopy.Results The result indicates that As lesions were significantly improved in experimental group than in control one.Conclusion Our study indicats that fatty acid sodium of evening primrose oil shows remarkable preventive effects on experimental As in rabbits.