A 61 year old man complained initially about pain in the left lower leg with increasing swelling of the entire left leg. A slight swelling of the left ankle and knee and an erythematous skin change of 5 cm diameter developed and disappeared after a few hours. Two days later the patient complained about a sudden and massive weakness of the proximal skeletal muscles, progressive disturbance of swallowing, hoarseness and dark red to bluish erythematous skin eruptions on the right knee and buttock. An elevated creatinine-kinase and lactate-dehydrogenase were found. Dermatomyositis was diagnosed and treatment with high dose steroids initiated. Under this treatment the patients condition deteriorated dramatically. A treatment with plasmapheresis and cyclophosphamide was begun. A significant improvement occurred over three weeks. The patient was discharged, rehabilitated and remains free of symptoms on 10 mg cortisone. A neoplasm has so far not been detected.