There is an apparent correlation between the severity and duration of skeletal muscle involvement, cardiac manifestations and the extent of conduction system disease in polymyositis. Cardiac involvement during the course of polymyositis has been recognized as one of the typical features of skeletal muscle myositis. We report a patient with polymyositis in whom bifascicular block, prolonged P-R interval and congestive heart failure appeared three years before any clinical or laboratory evidence of active skeletal muscle myositis. To the best of our knowledge, this is the first report of polymyositis where cardiac manifestations preceded those of skeletal muscle myositis.