It was generally known that over-ingestion of dietary orotic acid caused hepatic disorder by the lesion of fatty acid and cholesterol synthesis in rats. The present study was carried out to investigate the effects of dietary orotic acid on the lipid composition of serum, liver and kidney of rats. For the experiments, rats were fed with commercialized chow powder diet in the presence or absence of 1% orotic acid. The prepared diets were fed to male rats (Sprague-Dawley strain, $90{sim}100$ g of body weight for 21 days. According to the results, orotic acid treated group showed that each concentration of serum cholesterol, triglyceride and phospholipid was significantly decreased (p<0.05). The centration of liver triglyceride was significantly decreased (p<0.05). In the presence of 1% orotic acid, the weight of liver inclosed while that of kidney decreased. The treatment of orotic acid seemed to have no effects on the phospholipid composition in liver and kidney, except the kidney lysophosphatidylcholine. In the comparison of the phospholipid composition between liver and kidney, the levels of sphingomyeline and phosphtidylethanolamine in the kidney were higher than those in the liver. Among the composition of fatty acid in kidney, the concentration of linoleic acid (18 : 2) was increased, and the concentration of arachidonic acid (20 : 4) was decreased with the addition of the orotic acid.