Polymyositis is a treatable and curable disease. Unfortunately, patients with polymyositis are still frequently diagnosed as having muscular dystrophy. It is important to have a high index of suspicion of polymyositis, and to recognize that the detailed symptoms and signs and the overall picture are different from the relatively clear-cut pattern of the muscular dystrophies. Treatment of polymyositis is rewarding, although it frequently requires considerable resilience from both patient and doctor to achieve the best results. A detailed search for an underlying aetiology should be made, and a carcinoma should be suspected in elderly patients and those with dermatomyositis. In patients in whom polymyositis is related to a carcinoma, the latter may be at a stage where total excision is possible.