A two-minute slide agglutination test (Streptozyme) proved as sensitive in detecting streptococcal throat and skin infections as the combination of antistreptolysin O, antihyaluronidase, and antideoxyribonuclease B determinations. Acute phase sera from patients with rheumatic fever and glomerulonephritis were usually positive in high titer (400 or greater). Streptozyme was positive in low titer in 25% of patients with a variety of nonstreptococcal illnesses. Streptozyme thus appears to represent a simple, highly sensitive test for the detection of a multiplicity of serum antibodies to streptococcal products. It is clearly useful as a screening test. Its use for specific diagnosis, in lieu of a battery of streptococcal antibody tests, may prove feasible; however, more detailed data are required as to the specificity of the reagent before such recommendations can be formulated.