Introduction: Pneumopericardium is in fact a rare clinical condition. It is defined by an accumulation of air within the pericardial cavity and it was fi rstly mentioned by Bricheteau in 1844. The most frequent cause of pneumopricardium at adults is represented by the thoracic trauma. Methods: Case report. We report a case of a young patient of 25 years old, with no previous medical history, who was admitted at the emergency with a thoracic trauma caused by stabbing in the tightness of the heart. The resulted injury affected the teguments and costal cartilages, imposing a local treatment only. A routine ECG at admission was mentioning a slightly elevation of the ST segment within the V2-V4 derivations. The chest X-ray showed a pneumopericardium confirmed by the thoracic computed tomography scan. Results: The ECG directions performed daily bases pinpointed the evolutionary ECG modifi cations. Within the first 48 hours from hospitalization, a concave ST elevation was observed in the antero-sided area, followed by a convex ST elevation, which suggested acute myocardial infarction. The magnitude of the ECG modifications was not correlated with the pneumopericardium evolution. Therefore, the most important changes happened in the third day of evolution, although the pneumopericardium was spontaneously resolves aft er the fi rst 24 hours of hospitalization. The differential diagnosis was done by the acute coronary syndrome and the myocardial contusion. Pneumopericardium was self limiting and resolves spontaneously. Conclusions: Discussions. The electrocardiogram is the most on hand way of cardiological exploration, which should be used in the general assessment of a patient with thoracic trauma. Th e modifi cations of ECG, though not specific, can lead to the existence of a pneumopericardium. In this case, the ECG modifications were not so obviously at the time of interning, but became more visible aft er 2 – 3 days, although radiology pointed out the spontaneous presence of the pneumopericardium was spontaneously remitted aft er the first 24 hours of hospitalization. Key words: pneumopericardium, ECG.