Obese persons are more likely to be involved in vehicle accidents, probably because of the presence of sleep apnea. They are more likely to suffer chest, pelvis, and extremity fractures. Mildly overweight persons are less prone to intra-abdominal injury because of the protective effect of the abdominal fat, known as the cushion effect. Obese trauma patients are far more likely to develop in-hospital complications, especially pulmonary, renal, and thromboembolic complications. The BMI is an independent risk factor for morbidity and mortality after trauma. Because only limited data exist about the right clinical approach to obese trauma patients, it is necessary to rely on general knowledge about treating obese patients in the ICU. More research is needed to improve the treatment of obese trauma patients.