1. 1. Information was collected on 59 ambulatory cases of chronic rheumatic cardiac disease by obtaining at suitable intervals, histories, symptoms, leucocyte counts, pulse rates, measurements of temperature, physical examinations, electrocardiograms, x-ray photographs of the heart, and post-mortem reports. The group consisted of women between the ages of fifteen and forty-four years who were studied for a period of one to thirty-nine months, the average being 13.7 months. 2. 2. Rheumatic infection was probably active in each case either during observation or later. 3. 3. The most valuable single procedure for ascertaining the presence of rheumatic activity was the leucocyte count. Leucocytosis occurred in 85 per cent of the cases, its presence ranging from 11 to 100 per cent of the total number of counts. 4. 4. In some cases the rheumatic process appeared to be (a) either relatively quiescent or only slightly active, (b) in others, periods of inactivity alternated with others of activity, and (c) finally there were those in which activity was more or less continuous. These types occurred with equal frequency whether the rhythm was regular or there was auricular fibrillation. 5. 5. Patients manifesting frank signs and symptoms of acute carditis showed evidence of having had a preexisting active rheumatic state. 6. 6. Whether death occurred as the result of cardiac failure or of acute carditis, similar evidence of rheumatic activity was found. 7. 7. In three patients rheumatic activity and subacute bacterial endocarditis coexisted. 8. 8. The regular sinus rhythm gave way to auricular fibrillation in nine cases. In each instance the irregularity supervened during periods of rheumatic activity. 9. 9. In several cases, rheumatic activity continued for several years, leading to progressive cardiac damage and diminished cardiac reserve. 10. 10. In certain cases rheumatic activity is at times compatible with normal cardiac reserve.