Spontaneous pneumomediastinum (SPM) is a rare and benign clinical entity characterized by free air around mediastinal structures. Precipitating factors include violent cough, asthma, inhalational drugs, labor and exercise. We report a case of SPM due to achalasia which to the best of our knowledge, has never been reported. In achalasia, Valsalva maneuver might accompany severe vomiting. This causes alveolar rupture due to elevated intrabronchial and intra-alveolar pressure. Air tracks along the mediastinal spaces cause SPM. In our patient, there was no evidence of esophageal perforation. Tension pneumomediastinum and pneumothorax are complications of SPM.