We report here a case of Cogan's syndrome associated with systemic vasculitis as well as myeloperoxidase-specific antineutrophil cytoplasmic antibody (MPO-ANCA)-related glomerulonephritis. A 71-year-old woman with the diagnosis of aortitis syndrome and pulmonary fibrosis for 7 years, complained of vertigo and hearing impairment. A diagnosis of serous otitis media was made. Although steroid therapy was effective, the symptoms relapsed several times. Seven months after the first manifestation of aural symptoms, she developed painful red eyes bilaterally and proteinuria. On admission, perinuclear ANCA without cytoplasmic ANCA was detected by indirect immunofluorescence assay and MOP-ANCA was detected by enzyme linked immunosorbent assay using the 363 ELISA Unit. Renal biopsy showed necrotizing crescentic glomerulonephritis without immune deposits. A diagnosis of atypical Cogan's syndrome with systemic vasculitis and pulmonary fibrosis was made from the clinical and histological findings. As nephrotic syndrome progressed after admission, she was started on high-dose corticosteroid administration. Urinary protein and other symptoms, except for hearing acuity, improved in parallel with a decrease in the MPO-ANCA titer to normal values. While tapering the dose of corticosteroid, the MPO-ANCA titer increased again and dyspnea occurred. Although pulse methylpredonisolone therapy was performed, the patient died of respiratory failure complicated with sepsis. Postmortem lung biopsy showed pulmonary fibrosis and massive alveolar hemorrhage. The findings of this case study suggest that MPO-ANCA may be closely related to the pathogenesis of Cogan's syndrome.