The major types of idiopathic inflammatory myopathy include dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM) and immune mediated necrotising myopathy (NM). These myositides appear clinically, histologically and pathogenically distinct. DM, PM and immune mediated NM are responsive to immunosuppressive therapy, in contrast with IBM which is generally refractory to therapy. Greater understanding of the pathogenic bases of these disorders should hopefully lead to better treatment. We need well designed, prospective, double blind, placebo controlled trials in order to determine the best therapeutic options for these different disorders.