This review of the medical literature reveals that the incidence of rheumatic fever has been declining for at least 150 years, preceding by many decades the use of penicillin as a preventive measure. Simultaneously, the prevalence of rheumatic heart disease has diminished. Streptococcal upper respiratory tract infections remain common but with reduced severity and fewer subsequent cases of rheumatic fever. Scarlet fever has become relatively benign, with low mortality. Whether recent sporadic outbreaks of rheumatic fever due to known rheumatogenic strains of group A streptococci will have a significant effect on morbidity and mortality trends remains to be seen. Relatively high rates of rheumatic fever and rheumatic heart disease in developing countries are difficult to evaluate because of irregularities in reporting and investigative procedures.