The objective of this study was to assess the outcome of our series of idiopathic inflammatory myopathies (IIM) with special consideration of capillary damage as a prognostic indicator. We have classified our series of patients with the diagnosis of IIM according to the presence or absence of capillary damage in muscle biopsies, and determined their outcome by means of survival analysis statistical techniques. The follow-up of our patients seems to demonstrate that the patients without capillary damage present a more indolent form of IIM, with a slower response to treatment. The presence of capillary damage indicates a more acute disease, with more morbidity and mortality, but with a faster response to immunosuppression. The presence or absence of capillary damage seems to determine two forms of IIM with differentiated outcome and prognostic.