Vasculitis is a destructive inflammatory process affecting blood vessels. Pulmonary vasculitis may develop secondary to other conditions or constitute a primary idiopathic disorder. Thoracic involvement is most common in primary idiopathic large-vessel vasculitides (Takayasu arteritis, giant cell arteritis, Behçet disease) and primary antineutrophil cytoplasmic autoantibody-associated small-vessel vasculitides (Wegener granulomatosis, microscopic polyangiitis, Churg–Strauss syndrome). Primary pulmonary vasculitides are rare, and their signs and symptoms are nonspecific, overlapping with those of infections, connective tissue diseases, and malignancies. The radiologic findings in primary pulmonary vasculitis vary widely and can include vessel wall thickening, nodular or cavitary lesions, ground-glass opacities, and consolidations, among others. Diffuse alveolar hemorrhage usually results from primary small-vessel vasculitis in the lungs. To diagnose vasculitis, medical teams must recognize characteristic combinations of clinical, radiologic, laboratory, and histopathologic features.