BACKGROUND Wegener's granulomatosis (WG) is a granulomatous disease that can affect many organ systems. The most frequently involved organs include the upper and lower respiratory tract as well as the kidney. Cardiac involvement is rare. METHODS We report the case of a patient with grade 4 mitral insufficiency associated with severe WG. RESULTS Surgical analysis of the mitral valve revealed perforation of the anterior leaflet without evidence of endocarditis. Pathological examination of the anterior mitral leaflet revealed myxoid degeneration nodules and bacteriological examination was negative. As the perforated lesion was very close to the free margin of the anterior leaflet, valve replacement appeared a reasonable surgical option in a poor surgical candidate. Six months after the operation, the patient is doing well. CONCLUSIONS Wegener's granulomatosis is an autoimmune necrotizing vasculitis that can affect many organ systems. Cardiac involvement is rare. Heart in his globality can be affected by WG in many different ways. Cardiac valvular involvement in WG is rare. The aortic valve seems to be more frequently affected. Cardiologic investigations should have an important place at diagnosis and supervision.