Patients with bilateral femur shaft fractures are known to have a higher rate of complications when compared with those who have unilateral fractures. Many contributing factors have been considered responsible, however due to the heterogeneity of the studied populations solid conclusions cannot be substantiated. Patients included in our study were separated according to the presence of a unilateral (group USF) (n=146) versus bilateral femur shaft fracture (group BSF) (n=19)Endpoints of the study included the incidence of systemic (SIRS, Sepsis, Acute Lung Injuries) complications. The perioperative assessment included documentation of clinical and laboratory data assessing blood loss, coagulopathy, wound infection, and pneumonia. Local (wound infection, compartment syndrome etc.) and systemic complications (ALI, MOF, Sepsis) were documented. Statistical analyses were conducted to examine the relation between the occurrence of unilateral versus bilateral femoral fractures and variables indexing patient demographic characteristics and other indicators of initial injury severity. Independent sample t-tests were used to examine treatment group differences for variables that approximated a Gaussian distribution. For non-normal indicators of injury severity Mann-Whitney tests were performed. Pearson chi-square tests were performed for binary indicators of injury severity, except when expected cell counts did not exceed 5 participants. When this occurred, the Fisher exact test was used Evidence indicated that patients who suffered a bilateral femoral fracture were significantly more likely to have hemothorax and receive a blood transfusion upon admission to the hospital in comparison to patients who suffered a unilateral femoral fracture. Bivariate analyses also indicated that patients with bilateral femoral fractures exhibited a longer clinical recovery time and were more likely to experience clinical complications in comparison to those with unilateral fractures. However, there were no significant differences between the fracture groups in terms of the number of hours spent on a ventilator or the occurrence of pneumonia, acute lung injury, acute respiratory distress, sepsis, and multiple organ failure following surgery. Patients in borderline condition spent significantly more time in the ICU in comparison to those in stable condition. The high incidence of posttraumatic complications in poly-trauma patients with bilateral femur shaft fractures is caused by the accompanying injuries rather than by the additional femur fracture itself. It also documents that a thorough preoperative assessment can help differentiate those who have a high like hood of developing systemic complications from those who do not.