Kidney injury molecule-1 (KIM-1), a recently discovered transmembrane protein, is expressed in dedifferentiated proximal renal tubular epithelial cells in damaged regions. It may participate in the progress of renal injury or repair. Many studies have illustrated the different functions of KIM-1 in various renal diseases including protective functions in acute kidney injury and damaging functions in chronic kidney Disease. Studies have also shown the importance of this protein in prediction and diagnosis of acute renal injury as it starts to elevate after 6-12 hours of injury occurrence compared with creatinine which needs 2-3 days to rise. Urine and Serum levels of KIM-1, creatinine, urea and uric acid were measured in samples gathered from 85 patients divided into 4 groups as following: - Patients with acute renal injury (ARI). - Patients with chronic renal injury (CRI). - Patients who had acute renal attack after they had been diagnosed with chronic kidney injury. - High risk individuals from whom samples were collected 2 hours and 3 days after the occurrence of the acute injury. We found higher levels of KIM-1 in patient groups as compared to control group. We also found higher levels of KIM-1 in High risk individuals as compared to controls while the levels of creatinine and urea were still within the normal range. However, the three parameters were increased in samples taken after three days of injury. We found that urine and serum levels of KIM-1are elevated earlier in acute renal injury. Thus KIM-1 level can be used as a predictor of acute renal injury.