Background: Trauma is a major public health burble and is associated with a high mortality rate. Acute kidney injury (AKI) has been demonstrated to be accompanied by adverse outcomes among trauma cases and development of AKI is closely accompanied by increased mortality and length of stay (LOS). Objective: To determine the incidence and the associated risk factors of AKI in severe trauma patients and its outcome in the emergency intensive care unit (ICU). Patients and Methods: This was a prospective study conducted on 104 patients with severe trauma at Mansoura University Hospital. Entire cases were classified into 2 groups; AKI cases; patients who met the RIFLE criteria for AKI and non-AKI cases. Entire cases were subjected resuscitation followed by physical examination and laboratory investigations. In addition, trauma scores were assessed. Results: Forty-six percent of patients developed AKI by RIFLE criteria. There were significant differences among AKI and non-AKI in the context of sepsis, shock, coagulopathy and rhabdomyolysis. There were statistical significance serum creatinine (S.cr) levels at emergency room (ER), S.cr peak level at ICU, PH value at ICU, comorbidities, sepsis, shock, LOS, glomerular filtration rate (GFR) at ER and GFR with peak S.cr as independent predictors of AKI among sever trauma patients. Conclusion: Risk factors of trauma-associated AKI included rhabdomyolysis, coagulopathy, nephrotoxic drugs, shock and sepsis. Development of AKI after severe trauma is closely accompanied by increased mortality and LOS. Early detection of AKI and management of risk factors of AKI can improve the outcome.