To investigate the clinical characteristics of patients with post traumatic acute renal failure (ARF)effect of early renal replacement therapy on their propnosis, a case control study was carried out in 71 cases of post traumatic ARF and 40 cases of post operative ARF. The effect of early renal replacement therapy on prognosis was evaluated. The incidence of post traumatic ARF in traumatic patients was 1 06%, and 16 21% in ARF. Rhabomyolysis and hypovolemia were the most common causes of ARF. Respiratory failure and coma were the predisposing factors of ARF. The incidence of multiple organ failure was 85 9% and the mortality was 70 4%. Early renal replacement therapy might improve the prognosis. The mortality of patients with Post traumatic ARF remains high, renal replacement therapy should be given as early as possible.