Spontaneous pneumomediastnum is a very rare complication of systemic autoimmune diseases, The precise mechanism of pneumomediastinum in dermatomyositis is not well known. Pulmonary alveoli rupture secondary to interstitial pneumonitis or pulmonary infarctions consequent upon vasculitis are the suggested mechanisms, Among the idiopathic inflammatory myopathies, dermatomyositis and polymyositis show similar clinical manifestations except skin lesions. But pneumomediastinum occurs exclusively in cases with dermatomyositis, not in case with polymyositis. In a literature review, patients with dermatomyositis and pneumomediastinum had some characteristic features. As compared with dermatomyositis without pneumomediastinum, CK level was normal in about half and concomitance of interstitial lung disease and cutaneous vasculitis were very frequent. We experienced a case of dermatomyositis with spontaneous pneumomediastinum and subcutaneous emphysema, Thus we report that with a review of the literature and analysis of reported cases.