A rare development of acute inferior myocardial infarction is reported in a 23-year-old man with no previous history of cardiovascular disease. In an echocardiographic study a left intraventricular tumour was diagnosed. Cineangiographic study showed normal coronary arteries. The tumour, a myxoma, originating in the ventricular septum, was resected through the left atrium after the anterior leaflet of the mitral valve was detached. Postoperative course was uneventful and the patient remained healthy 48 months after surgery.