Although the incidence of rheumatic fever has declined significantly over the last decade, testing for antibodies to streptococcal extracellular enzymes maintains an important role in differentiating this disease from others with similar characteristics. Detection of antibodies to streptolysin O and DNase-B remain the more popular single antibody tests while the streptozyme test, which detects antibodies to five distinct streptococcal extracellular products, has been increasingly used in recent years as a screening test. Several new procedures detecting antibodies to different somatic antigens have been developed, the most promising of which seem to be anti-Group A carbohydrate tests. Because antibodies to the group A carbohydrate remain for several years in patients with persistent rheumatic valvular disease, this test should aid in the differentiation of rheumatic from non-rheumatic heart disease.