The present study was performed to estimate the chemical composition of rice bran and extracted rice bran oil (RBO). Also, physico-chemical parameters and fatty acid composition of RBO were evaluated. In addition, the biological effects of bioactive substances from rice bran oil as additives to the diets at different levels (i.e 10, 15, 20, 25 and 30%) on lipid profile, liver and kidney functions and histopathological findings of hypercholesterolemic rats. From the obtained results, it could be noticed that the rice bran  contains (on dry weight  basis) 11.18% moisture,  45.56% total carbohydrate,  11.40% protein, 18.36% total lipid,  6.31% crude  fiber and 7.21%  ash. The iodine value for the rice bran oil extracted in this study was found to be 102 g I2/ 100 g oil extracted, the saponification value was found to be 180 mg KOH/g. Acid value was 0.6 mg KOH/g, the refractive index was found to be 1.471. From the obtained results, it could be noticed that the rice bran oil extracted is dominated by the high percentage of polyunsaturated fatty acids (PUFA) than its saturated counterparts (42.74% oleic acid and 30.81% linoleic acid). On the other hand, triglycerides, serum total cholesterol, LDL-cholesterol and VLDL-cholesterol of the experimental rats were significantly decreased in all hypercholesterolemic rats fed diets containing different levels of rice bran oil extracted compared with the hypercholesterolemic group. Aspartate transferase (AST) and alanine transferase (ALT) of rats fed diets containing different levels of rice bran oil extracted were significantly lower as compared with rats fed hypercholesterolemic diet. Serum total protein and albumin for hypercholesterolemic rats fed different levels of rice bran oil were significantly higher than those for rats fed hypercholesterolemic diet. On the other hand, the histopathological findings indicated that the addition of rice bran oil at the different above levels to the rats containing cholesterol had slight effect on the microscopical lesions induced by feeding on high cholesterol diet.
Finally, from the obtained results and histopathological examination, it could be concluded that the addition of rice bran oil might improve the liver and kidney functions in hypercholesterolemic rats.