Background/Aim: Thoracic traumas cause life-threatening problems ranging from pulmonary contusion to multi-organ injuries. One of the most common complications of these traumas is acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). It is important to establish a biochemical marker to determine the severity of traumatic injuries and to monitor the inflammatory process. In this study, we aimed to measure the serum concentration of trimethylamine N-oxide (TMAO) and to investigate the diagnostic value of this metabolite in a low (3.31 joules), medium (6.62 joules) and high energy (9.93 joules) model of blunt thoracic trauma in rabbits. Material and methods: In this study, 27 New Zealand rabbits were divided into four groups: Control, low energy trauma group, medium energy trauma group, and high energy trauma group. Blood samples were collected at 1st, 12th and 24th hours after thoracic trauma. Results: Statistically significant differences in TMAO levels were found both within and between groups (p<0.0001). Conclusion: TMAO levels increased especially in the first hour following trauma and decreased at 12th and 24th hours compared to the first hour (in moderate and high energy trauma groups). These findings suggest that TMAO levels may be related to the severity and timing of trauma. In ALI resulting from blunt thoracic trauma induced at different energy levels, TMAO levels varied between groups and were associated with the timing and severity of trauma. These findings suggest that TMAO levels may be valuable in evaluating the prognosis of trauma and monitoring the inflammatory process.