The analysis comprised a total of 450 cases covering the period 2017–2018, in which death was a result of traffic accident, fall from a height, and crushing. Post-mortem examinations carried out at the Department of Forensic Medicine in Krakow consisted of conventional autopsy and post-mortem computed tomography (PMCT). The aims of the study were to evaluate the prevalence of pneumothorax in the study group, and attempt to identify a correlation between pneumothorax and the presence of specific types of thoracic injuries and the circumstances of trauma. Based on the PMCT data, pneumothorax was detected in 43% of cases in the study group. An important finding was the presence of tension pneumothorax with lung collapse and mediastinal shift in 16% of cadavers in the study group. The main injuries accompanying pneumothorax were found to be fractures of the rib cage (ribs, sternum, spine) and lung injuries. In 20% of cases, pneumothorax was shown to coexist with subcutaneous emphysema. In 11% of cases, marked asymmetry of the chest was noted. The circumstances of trauma resulting in the accumulation of air in the pleural cavities included primarily falls from a height and hits by a vehicle.