BACKGROUND The presence of severe associated injuries in flail chest complicates the interpretation of outcomes and the role of rib fixation. This study aimed to examine the impact of fixation in isolated flail chest patients. METHODS All patients diagnosed with flail chest injuries were queried from the National Trauma Data Bank (2016-2017). Patients who died within 72 hours, transferred from an outside hospital, had associated thoracic aortic injuries or significant extrathoracic injuries were excluded. Patients with rib fixation were propensity score matched 1:3 with similar patients treated nonoperatively and outcomes were evaluated. Multivariate analysis was used to identify independent predictors for mortality and prolonged mechanical ventilation. RESULTS Of 287,947 patients with rib fractures, there were 12,110 (4.2%) patients with flail chest. After exclusion, 5,293 patients with isolated blunt flail chest injuries were included in the analysis. Rib fixation was performed in 575 (10.9%) and 4,718 (89.1%) were managed nonoperatively. After matching, the mortality rate was significantly lower in the fixation group (2.0% vs 5.5%, p= 0.001). On multivariate analysis, rib fixation was associated with improved mortality (OR 0.355, p= 0.002). The timing of operation was not a significant independent risk factor for mortality. However, early fixation (≤72 hours) was associated with a significantly lower need for prolonged ventilation (>7 days). CONCLUSIONS Operative fixation in patients with isolated flail chest is associated with improved survival and should be considered liberally. The timing of fixation did not affect mortality, but early fixation was associated with a reduced need for prolonged mechanical ventilation.