Vasculitides are currently classified according to the size of the vessels involved and characteristic clinical and histopathologic findings. Antineutrophil cytoplasmic antibodies (ANCA) and other serologic tests have been used to further characterize small vessel vasculitides. Large vessel involvement in ANCA-associated small vessel vasculitides has been overlooked in the medical literature. Here, we report a case of fatal aortitis and aortic dissection in a patient with microscopic polyangiitis and review reported cases of large vessel involvement in ANCA-associated vasculitides since 1990. We have attempted to characterize this subgroup of patients. Large vessel disease in ANCA-associated vasculitis may present as stenosing large vessel arteritis, aneurysmal disease, aortic dissection, aortic rupture, aortic regurgitation, and death. Prominent perivascular inflammation may present as mediastinal, cervical or abdominal soft tissue masses. ANCA-associated large vessel disease should be considered in the differential diagnosis of these disorders. The epidemiologic, clinical and pathologic characteristics of these patients differ from those of the well-defined large vessel vasculitides such as giant cell (temporal) arteritis or Takayasu's arteritis. We suggest that large vessel involvement is part of the spectrum of ANCA-associated vasculitis rather than an overlap with other large vessel vasculitides. It occurs in both myeloperoxidase- and proteinase 3-positive patients with either Wegener's granulomatosis or microscopic polyangiitis, but has not been reported in Churg-Strauss syndrome. Large vessel vasculitis can precede small vessel vasculitis or occur in the absence of small vessel involvement. We hope this report will contribute to the ongoing development of classification systems for the vasculitic syndromes.