Abstract Development of caged-ball cardiac valve prostheses and subsequent experience with their use now allows effective surgical therapy for most patients with acquired valvular heart disease once they can no longer be managed satisfactorily by conventional medical therapy. When a patient reaches this stage in the course of acquired valvular disease, life expectancy without operation becomes seriously limited, and the quality of remaining life usually progresses rapidly toward total invalidism. It is within this context that results of prosthetic replacement of cardiac valves must be evaluated. Between April 1, 1962, and December 31, 1967, a total of 1,947 patients underwent prosthetic replacement of one or more cardiac valves in the Baylor University College of Medicine Affiliated Hospitals. No patient was refused valve replacement on the basis of endstage cardiac deterioration or concomitant coronary artery disease if the valve lesion was hemodynamically significant, and a large number of operations represented attempted salvage procedures. Over-all surgical mortality rate, including technical errors occurring in the developmental stage of these operations, was 17.7 per cent. As of December 31, 1967, there had been 295 late deaths, giving a cumulative mortality rate of 32.9 per cent, including all deaths from all causes, both related and unrelated to heart disease and valve replacement. Among the 1,307 surviving patients the great majority of those operated upon six months or more previously had returned to an active and meaningful life. Within the context of outlook for those patients without valve replacement, results of operation have been most gratifying.