Clinical features of infective endocarditis developed in a two year old boy. He had successfully undergone anatomical correction of complete transposition of the great arteries during the neonatal period. At routine investigation one year later he showed evidence of important supravalvar pulmonary stenosis. He remained symptom free until endocarditis developed. Streptococcus pneumoniae was isolated from serial blood cultures. Despite prompt treatment with specific intravenous antibiotic treatment the patient died of overwhelming sepsis. At necropsy the stenosed portion of the left pulmonary artery was seen to be the site of infection.