The purpose of the study was to find an effect of medium chain triglyceride (MCT)diet on the serum lipids and lipoprotein of Sprague-Dawley rats when the were fed with cholesterol. All experiment-groups were fed with different diet such as soybean oil, shortening,MCT and MCT mixed with oil respectively. After fed to each group, the levels of serum lipids and lipoprotein among fed rats were examined and the data from the experiment were compared with a control group. The results obtained from the study are as follows : (1) The average boby weight gain in MCT diet and soybean oil diet groups were lighter than that of the control group, while the food efficiency ratio in each experimental diet group was almost same as than in the control group. (2) Total cholesterol levels in serum of all experimental diet groups were lower than that of the control group except the level in shortening diet group. Especially, the levels of total cholesterol in MCT diet and soybean oil diet groups were significantly lower than that of the control group. (3) VLDL, LDL-cholesterol levels of all experimental groups were almost same except the case of the MCT diet and soybean oil diet group which was significantly low. (4) The ratio of VLDL, LDL-cholesterol to HDL-cholesterol, so called, atherogenic index in serum of MCT and soybean oil diet groups were significantly lower than that of the control group. (5) The ratio of total cholesterol to phospholipids in serum of MCT diet group was decreased, because total cholesterol levels were decreased more than phospolipid levels. (6) The ratio of the serum VLDL, LDL to HDL in MCT diet group. in MCT and soybean oil mixed diet group, and in soybean diet group was decreased. In other wards, it means that the decrease of the serum VLDL, LDL in each group and the increase of the serum HDL.