Sweet potato is one of the most important vegetable crop in Egypt. Leaves of these plants are rich sources of proteins, fibers and pigments. A special interest was given to plant protein as hypocholesterolemic agent. They are also used for nutrition and food additives. Leaf protein concentrate (LPC) was prepared by using HCl 1.0 N. In addition, leaf protein isolate (LPI) was extracted by using sodium hydroxide. The percentage of protein in LPC was 40.53%. While in LPI, it amounted to 86.63 %. The amino acids content of LPI was determined using amino acid analyzer. The first limiting amino acids were cysteine and methionine. Methionine:glycine ratio and arginine:lysine ratio are important for their hypocholesterolemic effect. In LPI; methionine: glycine ratio was low (0.29) compared with casein (1.57), while arginine: lysine ratios was high (1.30) compared with casein (0.46). Phenolic compounds and tannins were also determined in LPC, LPI and fibrous residues.                 The present study was carried out on rats in order to evaluate the biological value of (LPC) and (LPI) from sweet potato. Casein (10%) in basal diet was replaced by the same amount of protein found in LPC and LPI. Albino rats (18) were fed on diet containing LPC and LPI, in order to determine the gain in body weight, food efficiency ratio, protein efficiency ratio and biological value. The lipid fractions (total lipids, cholesterol and triglycerides) were determined in serum and liver of rats fed on LPC and LPI compared with casein. In rats fed diets containing LPC, the total lipids in serum decreased from 405.6 to 291.41, total cholesterol from 126.32 to 91.21 and triglycerides from 147.92 to 113.45 mg/dl. In case of LPI, the total lipids in serum decreased from 405.6 to 344.5, total cholesterol from 126.32 to 105.98 and triglycerides from 147.92 to 125.7 mg/dl.   LPC and LPI decreased lipid fractions in liver. Low methionine:glycine ratio and high   arginine:lysine ratio were found to lower cholesterol. The effect of LPC and LPI on transaminase enzymes, protein and urea in serum were determined. No deleterious effect on liver or kidney could be detected.