The typical lesions of Wegener's granulomatosis in the lung consist of necrotizing granulomatous inflammation associated with a necrotizing vasculitis. We report an unusual case in which massive pulmonary hemorrhage was the initial manifestation. An open-lung biopsy showed intraalveolar hemorrhage and a necrotizing capillaritis, but no granulomas and no vasculitis involving arteries or veins. The diagnosis of Wegener's granulomatosis was established only at autopsy, when necrotizing granulomas and vasculitis were found. This case emphasizes that Wegener's granulomatosis should be considered in the differential diagnosis of pulmonary hemorrhage and necrotizing capillaritis.