This study investigates the changes in serum levels of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) in patients with severe polytrauma, aiming to explore their potential association with infectious pulmonary complications and mortality. The research involved 25 patients with a mean Injury Severity Score (ISS) of 40.2±9.2 and 7 healthy volunteers. The levels of mtDNA and nDNA were measured at various time points post-injury, including 12 and 24 hours, and on days 3, 5-7. Key findings include a more than 2.5-fold increase in mtDNA levels in deceased patients compared to survivors, while nDNA levels showed no significant differences. Within the first 12 hours, the mean mtDNA level in patients with pneumonia was 34 times higher than in those without, and it continued to rise further. In contrast, nDNA levels increased in both groups but were 2553 times higher in patients with pneumonia 24 hours post-injury, compared to 5-fold higher in those without pneumonia. The study concludes that measuring mtDNA and nDNA levels within the first 24 hours of hospital admission can predict the development of infectious bronchopulmonary complications and guide timely etiological therapy. Further research is recommended to validate these findings.This study investigates the changes in serum levels of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) in patients with severe polytrauma, aiming to explore their potential association with infectious pulmonary complications and mortality. The research involved 25 patients with a mean Injury Severity Score (ISS) of 40.2±9.2 and 7 healthy volunteers. The levels of mtDNA and nDNA were measured at various time points post-injury, including 12 and 24 hours, and on days 3, 5-7. Key findings include a more than 2.5-fold increase in mtDNA levels in deceased patients compared to survivors, while nDNA levels showed no significant differences. Within the first 12 hours, the mean mtDNA level in patients with pneumonia was 34 times higher than in those without, and it continued to rise further. In contrast, nDNA levels increased in both groups but were 2553 times higher in patients with pneumonia 24 hours post-injury, compared to 5-fold higher in those without pneumonia. The study concludes that measuring mtDNA and nDNA levels within the first 24 hours of hospital admission can predict the development of infectious bronchopulmonary complications and guide timely etiological therapy. Further research is recommended to validate these findings.