To assess the prevalence and severity of Doppler-detected valvular regurgitation, as assessed by multiple Doppler modalities, in patients with structurally normal hearts, we analyzed Doppler echocardiograms in a consecutive sample of 206 referred patients who were found to have completely normal M-mode and two-dimensional echocardiograms. Valvular regurgitation was detected by Doppler in 94 percent, and 56 percent had regurgitation in at least two valves (mitral, tricuspid, and/or aortic). Mitral, tricuspid, and aortic regurgitation was detected in 73 percent, 68 percent, and 12 percent, respectively, with moderate regurgitation occurring in 6 percent, 5 percent, and 2 percent, respectively. The presence of mitral and tricuspid regurgitation was not related to age, although the prevalence of moderate regurgitation was three times more prevalent (p < 0.05) in those > 50 years old compared with those < or = 50 years. Aortic regurgitation was two to three times more prevalent (p < 0.01) in patients > 50 years compared with younger subjects, and moderate aortic regurgitation was three times more prevalent in older patients. Of those with measurable right-sided cardiac pressures, estimated right atrial pressure was < 10 mm Hg in 93 percent of patients, and estimated pulmonary artery systolic pressure was < or = 30 mm Hg in 57 percent of patients. Estimated right atrial pressure was > 10 mm Hg in only 7 percent, and only 13 percent had estimated pulmonary artery systolic pressure > or = 40 mm Hg. These data indicate a very high prevalence of trivial and mild mitral and tricuspid regurgitation in patients with otherwise "normal" hearts, suggesting that these findings are physiologically normal. These data should be considered when addressing management in patients with Doppler-detected valvular regurgitation in order to prevent "iatrogenic heart disease."