Doppler echocardiography has become a very useful and widely employed imaging technique for evaluating valvular regurgitation, and has thus lead to the discovery of regurgitation in unexpected subjects. In this study, we examined left-sided valvular regurgitation in 31 healthy subjects, 35 patients with hypertension and 43 patients with old myocardial infarction by Doppler echocardiography. Aortic regurgitation was found in 3% of healthy subjects, 8% of hypertensive patients and 5% of patients with myocardial infarction. Mitral regurgitation was found in 35% of healthy subjects, 69% of hypertensive patients and 84% of patients with myocardial infarction. The pathogenesis of mitral regurgita tion in hypertension is considered to be the impairment of the mitral leaflets, since neither anatomical nor functional abnormalities were found in the subvalvular mitral apparatus. Left ventricular dilatation and asynergy near the papillary muscles were related to the pathogenesis of mitral regurgitation in myocardial infarction. Mitral regurgitation in healthy subjects and hypertensive patients was mild and resistant to afterload stress, suggesting that it was less pathological. On the other hand, mitral regurgitation in myocardial infarction was easily worsened by afterload stress. Doppler echocardiography has thus provided us with new insights into valvular regurgitation in healthy subjects and patients without rheumatic valvular disease. © 1990, The Japanese Circulation Society. All rights reserved.