We determined the outcome of acute rheumatic fever in 85 children from North India who had received regular antistreptococcal prophylaxis after their first attack. By the end of the 5-year follow-up, 33 patients had rheumatic heart disease. Mitral insufficiency, the most common valvular lesion, appeared in 91% of the patients, whereas mitral stenosis developed in only 18%. Initial carditis, congestive heart failure, cardiomegaly or moderate-to-severe mitral insufficiency significantly increased the risk of rheumatic heart disease (p less than 0.001). The recurrence rate of acute rheumatic fever in children who received continuous prophylaxis was 0.006 per patient-year. Most recurrence (92%) mimicked the first attack and produced further cardiac damage in five patients with carditis and in one patient with chorea. Cardiac status during the first attack of rheumatic fever and the continuity of prophylaxis were the major determinants of outcome. Statistical comparisons disclosed that with continuous prophylaxis, the prevalence rate, evolution and clinical spectrum of the sequelae of acute rheumatic fever in children from India do not differ significantly from those in the West.