The prevalence of valvular regurgitation in a large population with structurally normal hearts remains unknown. From the computer database of the echocardiography laboratory of the hospital, 7209 records containing results of both two-dimensional and Doppler echocardiographic examinations were identified, from which 867 (12%) with no structural abnormality on two-dimensional echocardiograms were obtained for analysis. Of these 867 records, 291 (34%) had evidence of regurgitation by Doppler technique in at least one cardiac valve. Mitral regurgitation was found in 167 (19%), tricuspid regurgitation in 151 (17%), pulmonic regurgitation in 45 (5%), and aortic regurgitation in 29 records (3%). Regurgitation of just one valve was the most common and occurred in 207 records (24%). This was followed by regurgitation of two valves (69 records, 8%), three valves (13 records, 2%), and four valves (two records, 0.2%). The prevalence of mitral, tricuspid, and aortic regurgitation was found to increase significantly with increasing age, as was the prevalence of regurgitation involving multiple valves. In 98% and 95% of mitral and tricuspid regurgitations, respectively, the jets were confined to the proximal one fourth of the atria, suggesting only trivial or mild regurgitation. Thus valvular regurgitation occurs not uncommonly in patients with structurally normal hearts referred for echocardiographic evaluation. These findings caution against the inappropriate diagnosis of clinical disease in the many patients who fall into this category. The increasing prevalence of valvular regurgitation with increasing age suggests that a wear-and-tear phenomenon rather than a congenital cause is involved in most instances.