A 28-year-old male patient suffering from Wegener's granulomatosis died suddenly with signs of cardiac failure after clinical symptoms had basically subsided under chemotherapy. Autopsy revealed pulmonary granulomata, necrotizing vasculitis of the lungs and kidneys, focal and segmental necrotizing glomerulonephritis, and diffuse granulomatous and necrotizing giant cell myocarditis. Histological confirmation of inflammation of the heart in Wegener's disease has rarely been reported. Although cardiac involvement in Wegener's granulomatosis sometimes is suspected, it is usually thought to have no major impact on the course of the disease. By its dramatic clinical and morphologic presentation this case illustrates that the heart, in addition to the lungs and kidneys, may determine the outcome of the idiopathic granulomatous vasculitis of Wegener.