Objective: To evaluate the prognostic value of arterial blood gas (ABG) indices, especially base excess (BE), regarding the severity of traumatic injury.Methods: A total number of 96 trauma patients with fractures of femur and pelvis were included in this study. Demographic characteristics and clinical information of samples were recorded. The results of ABG test and hemoglobin (Hb) were evaluated at two time intervals (on admission and 6 hours later). The outcome of the patients was evaluated at the end of the study (dead or alive). The ABG indices included O2 saturation (O2Sat), PH, PO2, PCO2, bicarbonate (HCO3) and base excess (BE). The mean of the hemodynamic and ABG indices were compared between those who were discharged and mortality cases. The confounders were compensated using a multivariate logistic regression model.Results: Overall 94 trauma patients with long and pelvic fractures were included. There were 69 (73.4%) men and 25 (26.6%) women among the patients with mean age of 37.43 ± 20.07 years. The mortality rate was 10 (10.6%). The most common mechanism of injury was motorcycle accident in 41 (43.6%) and car collision in 43 (45.7%) patients. We found that mortality was significantly associated with amount of FFP transfusion (p=0.005), but was not associated with amount of transfused packed cells (p=0.113). We also found that mortality was associated with lower BP after 6 hours of admission (p=0.001), higher HR on admission (p=0.036), lower HR after 6 hours (p=0.017), lower O2Sat on admission (p<0.001), higher PCO2 after 6 hours and lower BE on admission (p=0.025). Conclusion: The ABG indices including O2Sat, BE and PCO2 are considered prognostic determinants of outcome in trauma patients with long and pelvic fractures. These findings can be considered as fundamental studies to achieve new diagnostic methods.