The following work was carried out in order to determine whether one strain or a group of strains of streptococci exist which could be classed as rheumatic on the basis of the skin reactions in rheumatic subjects, and further to find if any immunologic characters were common to the varied types of streptococci which may be isolated in cases of rheumatic fever and chorea. Attempts made to isolate streptococci from the blood stream were largely unsuccessful. Thirty-three blood cultures were made from twenty-nine subjects, and the technic advocated by Clawson1was employed. All of the subjects were acutely sick with rheumatic manifestations, and the fever at the time of culture varied between 38.6 and 40 C. (101.5 to 104 F.). All except four had cardiac involvement. Eleven had pericarditis and ten had subcutaneous nodules. The cultures were kept from four to six weeks and examined semiweekly. Contamination with air organisms