Effect of perilla oil on the fatty acid composition, ACAT and HMG-CoA reductase in the liver microsomes, or cholesterol and protein in serum of rabbit were examined. 1. The content of total protein in serum was almost same amount of both groups, but ${alpha_1}-globulin$ and r-globuline were incresed or ${eta}-globulin$ was decresed compared with control. 2. The content of high density lipoprotein incresed, and the content of low density lipoprotein decresed in lipoprotein. 3. Total cholesterol and triglyceride were decresed, and the content of phospholipid was incresed. 4. Perilla oil did not effect for changing blood glucose and $Na^+,;K^+$ electrolytes. 5. Perilla oil did not effect for changing serum GOT and GPT in rabbit. 6. The activity of ACAT decresed and the activity of HMG-CoA reductase incresed. The activity of ACAT and HMG-CoA reductase in liver microsomes were reciprocal. 7. There were arachidonic acid 20:4, eicosapentaenoic acid 20:5, and docosahexaenoic acid 22:6 in the liver microsomes of rabbits. These highly polyunsaturated fatty acids were convented from linolenic acid 18:3 n-3.