though an association between the group A beta hemolytic streptococcus and rheumatic fever has been recognized for more than half a century, many important issues about this relationship remain incompletely defined. The initiating pharyngeal throat infection and the difference between true infection and the relatively harmless streptococcal “carrier state” are not yet understood. Many properties of the organism itself largely remain a mystery. While much has been written about “rheumatogenecity” of certain streptococci, the precise mechanism for inducing “rheumatogenecity”is unknown. Nor is there sufficient evidence to understand the role of “antigenic mimicry” in the pathogenesis.With the introduction of molecular techniques into the basic science laboratory, the nurmer of different streptococcal types (based either on the M protein or the emm gene) has almost doubled during the past ten years, making the problem even greater since little is known about the relative importance or epidemiology of these newly described types.