Muscle disorders (myopathies) are rare in all age groups. They may be inherited or acquired. Inherited disorders presenting for the first time in middle age and later include myotonic dystrophy, oculopharyngeal muscular dystrophy and mitochondrial disorders, particularly chronic progressive external ophthalmoplegia. Acquired disorders are more common and most are amenable to therapy, an important exception being inclusion body myositis, which is also the most common myopathy presenting over the age of 50 years. The idiopathic inflammatory myopathies, dermatomyositis and polymyositis, respond to immunosuppressant drug therapy. Dermatomyositis may be a paraneoplastic condition and surveillance for cancer is essential. Clinical assessment alone will frequently suggest the correct diagnosis but confirmation may require muscle biopsy or DNA analysis. Drug-induced myopathy is under-recognized but particularly important in the older population because of multiple drug therapy and the explosion in the use of statins. © 2012 John Wiley & Sons, Ltd.