Spontaneous pneumomediastinum (SPM) is defined as the presence of interstitial air in the mediastinum without any apparent precipitating factor. We present a case of 23 year old male patient, who has been referred to our outpatient clinic with the complaints of sudden chest pain, dyspnea followed by pneumonia and was diagnosed as SPM. The patient was treated with ampicillin sulbactam (4 gr/day) and methylprednisolon (20 mg/day) for 4 days. and oral intake was stopped during treatment. Post treatment, it was observed that the crepitations were disappeared thoroughly and vesicular sounds were heard by oscultation. The control values of arterial blood gas was as following: pH:7,39 pO2:95 mmHg, pCO2:37 mmHg, SaO2: %97. In the 5th day his oral intake was started and he was discharged.