Thoracic trauma is the most important type of emergency traumas, which can cause complications. Accurate follow up of patients, repeated examinations and regular paraclinical tests are helpful in the prevention of serious complications in these patients. Regular and control thoracic radiographies are performed in many centers with interval of 6-8 hours to follow up complications in stable patients. There are different ideas about follow up procedure and interval between actions. Some believe that even 3 hours is adequate for monitoring in patients with asymptomatic penetrating trauma (4).