This report describes autopsy findings of eosinophilic polymyositis in a 29-year-old woman. She complained of muscle pain and tenderness. A serum examination disclosed elevated creatine kinase, and echocardiography showed lowered cardiac function. Electromyography demonstrated myopathic potentials, and the skeletal muscle biopsy revealed degeneration of muscle fibers accompanying marked eosinophilic infiltration. Peripheral eosinophilia was not prominent. A systemic examination excluded possible etiologic factors, such as hypereosinophilic syndrome, collagen vascular diseases, or parasites. The patient died of heart failure after a 4-month clinical course. The autopsy disclosed a set of histological changes indicating tissue injuries, that is, loss of muscle fibers, interstitial fibrosis, and/or infiltrates of lymphocytes not only in the skeletal muscles and heart but also in various visceral organs. Eosinophils were sparsely scattered. These results indicate that the overrun of eosinophils underlying eosinophilic polymyositis, regardless of the presence of hypereosinophilic syndrome or other systemic disorders, could involve wide-ranging visceral organs.