The current study was done to determine changes in hematological, renal and hepatic parameters induced by moderate and severe burn injuries. Patients and Methods: the study was done during the period from march 2016 to December 2016 on 60 adult patients, who were admitted at burn unit of Assiut university hospitals with burn area ≥ 20% of body surface, and 20 healthy adults considered as control. The patients and control were investigated for renal and hepatic functions, serum electrolytes (Na+ & K+) and blood picture. Results: Concerning the renal function, it was found that blood urea and serum creatinine levels were significantly increased in burn patients in comparison to control, the blood glucose level showed maximum significant increase on the first day then decrease gradually on the 3rd and 5th days post burn. Regarding serum electrolytes, the serum Na+ & K+ levels decreased in a significant manner during the 3rd and 5th days post burn, the blood picture showed a significant increase in (WBCs) and Neutrophil count ratio in burn patients in comparison to control, the Platelet count showed a significant reduction in burn patients throughout the whole period of the study while (Hb) level showed significant lowering during the 3rd and 5th days post burn, the RBCs count showed a significant increased on the 1st day, then decreased significantly on the 5th day post burn, the (HCT) value showed a significant decrease on the 3rd and 5th days post burn. Regarding the liver functions, the serum levels of (ALT), (AST) and (ALP) showed a significant increase in burn patients in comparison to control, the serum protein and albumin showed a significant decrease in burn patients, the prothrombin concentration was reduced and Prothrombin time was prolonged significantly, while the (INR) showed a significant increase in patients in comparison to control.