Background: Poly trauma is a major cause of morbidity and mortality in both developed and developing countries. The aim was to investigate whether renal Doppler RI changes occur early with posttraumatic bleeding and whether the renal Doppler RI may enable accurate prediction of occult hypoperfusion and thus be predictive of the development of hemorrhagic shock in polytrauma patients.Methods: It was a prospective study involving patients admitted in the causality and evaluated by radiology department. Study was done in a period of 6 months from June 2016-December 2016. Renal Doppler RI was measured in 48 hemodynamically stable adult patients admitted in emergency because of polytrauma.Results: 26 patients developed hemorrhagic shock, and 22 did not. Hemorrhagic shock group, as compared with the nonhemorrhagic shock group, had higher renal Doppler RI (mean, 0.79±0.11 [standard deviation] vs 0.61±0.2; P<0.01), injury severity score (mean, 33±12 vs 25±9; P<0.01), and standard base excess (mean, -4.0mEq/L±4 vs 1mEq/L±3; P≤0.05) values. At logistic regression analysis, a renal Doppler RI greater than 0.9 was the only independent risk factor for progression to hemorrhagic shock (P<0.001).Conclusions: Renal Doppler RI measurement may represent a clinically useful non-invasive method for the early detection of occult hemorrhagic shock.