THIS STUDY has been carried out to extract whey protein concentrate (WPC) from sweet whey and to study the chemical composition, amino acids composition, amino acid scores and to investigate the possible role of WPC in ameliorating some biochemical disorders induced in γ-irradiated rats. Animals were divided into 4 groups. Group 1, fed on normal diet during experimental period. Group 2, fed on diet containing 15% WPC instead of soybean protein. Group 3, rats exposed to whole body γ-radiation with single dose of 5 Gy and fed on the normal diet. Group 4, rats exposed to 5 Gy then fed on diet containing 15% WPC. The rats were decapitated 14 and 28 days post irradiation. Chemical analysis of WPC revealed that it contains high amounts of protein (44%), total amino acids (71%) and all essential amino acids (EAA), phenylalanine (37%), isoleucine cystine and threonine were the major EAA and high amounts of sulphur amino acids. Methionine gave rich chemical score (102.67%) also, isoleucine (119.95%) and phenylalanine+ tyrosine gave maximum chemical score (198.8%), respectively. Exposure to γ-irradiation caused significant elevation of serum cholesterol, triglycerides, low density lipoprotein (LDL), lipid per oxidation end product (TBARS) and iron (Fe) with significant decrease in high density lipoprotein (HDL), glutathione (GSH) and catalase (CAT) in serum. Also, irradiated rats had significant decrease in copper (Cu), magnesium (Mg) and zinc (Zn) in serum. The histological examination of cardiac tissue showed severe structural damage. Irradiated rats fed on WPC revealed significant improvement of some biochemical parameters. It could be concluded that WPC must be added to diet for reducing radiation injury via metabolic pathway.