Although obesity and trauma both are common in the general population, discussion of the care of the critically injured obese patient has been relatively absent. Obesity is associated with significant clinical and occult multisystem disease. Because host factors are key determinants of post-traumatic course and outcome, obesity appears to be a marker of high risk. Obesity should be considered with age, pregnancy, cardiopulmonary disease, and substance abuse as a host factor that has significant post-traumatic ramifications. Only by employing a comprehensive, multidisciplinary approach to the critical care management of such patients will post-traumatic complications be prevented and treated effectively.