Subcutaneous generalized edema associated with dermatomyositis (DM)/polymyositis (PM) is extremely rare. Herein we report a case of severe subcutaneous generalized edema complicating DM. A 78-year-old woman was hospitalized in our department because of massive edema in the four limbs. Elevated muscle enzymes, heliotrope rash, results of electromyography, and muscle biopsy confirmed the diagnosis of DM. The absence of other diseases that could cause the symptoms indicated that massive edema was correlated with the pathophysiology of DM. Although myopathy and edema responded well to oral prednisolone, dysphagia persisted. We conclude that subcutaneous generalized edema can occur during the course of DM/PM, and subcutaneous vasculopathy may be involved in the pathogenesis of DM/PM. © Japan College of Rheumatology 2007.