We describe a 58-year-old female with BOOP associated with polymyositis. Four months prior to the appearance of distinctive manifestation of polymyositis, she presented with a two-week history of cough, dyspnea on exertion, and fever. Chest roentgenogram demonstrated bilateral basal infiltrative shadows. The patient was treated with prednisolone, 30 mg/day because of progressive hypoxemia. Open lung biopsy revealed organizing masses of granulation tissue extending from the respiratory bronchioles into the intra-alveolar spaces, which was consistent with BOOP. She developed muscle pain in her legs, fever, dry cough, hypoxemia, and high CPK value in the course of tapering of steroid dose. The findings of biopsy from the left rectus femoris muscle were compatible with polymyositis. Retrospective study of the patient's serum on admission showed positive anti Jo-1 antibody.