We report the case of a 19-year-old man with dermatomyositis who developed abdominal pain and anuria. The examination revealed bilateral ureteral stenosis. The patient also developed multiple ulcerations of the duodenum with perforations. The clinical feature was considered to represent that of juvenile dermatomyositis, which is characterized by systemic necrotizing vasculitis. Rheumatologists should be alerted about this serious complication in patients with childhood or young adult dermatomyositis presenting with abdominal complaints.