Group A streptococcus is an uncommon cause of infective endocarditis. We report five probable cases during a 10-year period (1980-1989) from a 750-bed community-teaching hospital. None of the patients were drug abusers. Group A streptococcus is the cause of infective endocarditis in between 0 and 5% cases in reported series. Since the introduction of penicillin 69 cases of group A streptococcus endocarditis have been reported in the literature. Clinical details of 14 patients, none of whom were drug abusers, are available. Included are our five cases. Eight patients had no underlying valve lesions. The overall mortality was 21% but only 15% for patients treated approximately. Among the 25 reported IV drugs abusers with group A streptococcus endocarditis and known valve involvement, right-sided heart valves were involved in 19 and left sided in six. The overall mortality was 9%.