From ten patients aged 15 to 40 years with chronic rheumatic valvular disease and histologically proved Aschoff bodies of active rheumatic myocarditis, the valves were evaluated for incidence, distribution and degree of severity of active inflammation. Prior to death, there had been clinical evidence of active rheumatic fever. In each case, active rheumatic valvulitis was present in at least one valve. Of the individual valves studied, 83% were involved by active inflammation of the leaflets or the anulus or both. The aortic valves was involved in 100% of cases, the mitral valve in 86%, the tricuspid valve in 78% and the pulmonary valve in 70%. The mitral and aortic valves were most frequently involved, but the mitral and tricuspid valves were most severely involved when affected. In every case, active rheumatic lesions of the left atrial appendage were present, but these tended to be less widely distributed than the myocardial Aschoff bodies. The high incidence of active valvulitis supports the concept that chronic fibrosing rheumatic valvular disease results from recurrent active inflammation. Such inflammation may occur without clinical suspicion of active rheumatic fever.