Abstract: Objective: To acknowledge the possible associated factors of dermatomyositis and pneumomediastinum. Methods: Two patients with dermatomyositis complicating spontaneous pneumomediatinum were presented and the related literatures were reviewed. Results: By analysing the clinical information of 13 cases from literatures and our own cases, we found that 72.7% of these patients had normal CPK at the time when pneumomediastinum happened; 38.4% had remittent complications and 46.2% died; 53.8 % had previouse pulmonary diseases. There were obvious skin changes in the two cases. Moreover, one of ours and other 4 patients from literatures had multiple skin ulcers indicating the cutanuous vasculitis was active. Conclusion: Dermatomyositis patients with previous pulmonary diseases, normal or slightly elevated serum muscular enzymes and dominant skin changes are more likely to suffer from complication of pneumomediastinum than those with obvious muscular damage and polymyositis patients. The reason is probably because of the existence of pulmonary fibrosis and active vasculitis.