Background. The injured with polytrauma are classified as extremely severe patients, as their emergency care and intensive care is followed by significant difficulties, frequent development of complications, high mortality and survivors disability. Objective. This study is aimed to evaluate the effect of lipid peroxidation in heart, lungs, liver and blood of rats in early and late periods of combined traumatic injury of chest and hips and to establish their influence on the development of multiple organ failure. Methods. The study was conducted on 70 adult male white nonlinear rats. It was determined the content of lipid hydroperoxides and concentration of TBA-active products in erythrocyte mass, heart, lungs and liver. Results. The data prove activation of free radical oxidation at the first day of post-traumatic period. Analysis of the data evidences the increase in of lipid hydroperoxides (HPL) rate in liver homogenate in group E1 in 1.5 times, in all subsequent periods of the research the increase in rate fluctuated within 1.9-2.0 times. In blood and heart the HPL rate increased twice in group E1, reached maximum in group E2 and gradually decreased till the end of the experiment, data exceeded the control group. The highest level of HPL was determined in lung tissues (r≤0.01). In the post traumatic period the highest TBA-AP was detected in lungs and liver. Conclusions. In case of simulated trauma (injury of chest with fractures of both hips) hyperactivation processes of free radical oxidation is observed in 1 day, reaching a peak in 7-14 days of post-traumatic period in blood, tissues, liver, heart and lungs if compared to the control group causing multiple organ failure.