BACKGROUND Streptococcus thoraltensis is a rare cause of human disease. This report describes a patient with infective endocarditis caused by S. thoraltensis and complicated by ischemic stroke. CASE REPORT A 68-year-old man was admitted for a 12-day duration of fever. He had a history of severe aortic valve stenosis, for which he underwent prosthetic valve replacement, and type 2 diabetes mellitus. Echocardiography revealed vegetation attached to the right coronary cusp of the prosthetic aortic valve and rupture of the sinus of Valsalva into the right ventricle. Blood cultures were positive for S. thoraltensis. He experienced an ischemic stroke involving the vegetation of the aortic valve and died of acute heart failure. CONCLUSIONS S. thoraltensis may be considered an emerging pathogen in patients with infective endocarditis.