Blunt renal trauma patients often have multiple injuries. We retrospectively analyzed factors that could be predictive of outcome and the need for nephrectomy in this population. Blunt renal injury patients admitted to a Level I trauma center from January 1989 to July 1997 were identified and their charts reviewed. Multiple factors were examined. Using logistic regression analysis, factors predictive of mortality and the need for nephrectomy were determined. Of 11,847 trauma patients admitted, 95 (0.80%) suffered blunt renal injury. Mean age and ISS were 31.4 and 23.7, respectively. The number of deaths and nephrectomies was 11 and 10, respectively. Higher renal injury grade, as well as higher ISS values and 24-hour transfusion needs, directly correlated with the need for nephrectomy. Greater age, higher ISS, and higher 24-hour transfusion requirements lowered probability for survival. Patients with blunt renal injuries often sustain multiple injuries. The grade of renal injury, the overall injury severity of the patient, and the requirement of blood transfusion are the primary factors in determining the patient's need for nephrectomy and overall outcome.