To determine the prevalence of valvular regurgitation in children (from birth to 14 years old) with structurally normal hearts, the records of 1360 consecutive patients referred for echocardiographic and Doppler examination were analyzed. A total of 461 (33.9%) patients were found to have structurally normal hearts. Flow patterns across the four valves were examined by pulsed, continuous-wave, and color Doppler imaging techniques. Regurgitation was detected in 124 (26.9%). Pulmonic regurgitation was most commonly found and was detected in 101 (21.9%) patients, tricuspid regurgitation in 29 (6.3%), and mitral regurgitation in 11 (2.4%). Aortic regurgitation was not found. Regurgitation of one valve occurred in 106 (23.0%) patients and of two valves in 18 (3.9%) patients. No patient had regurgitation of more than two valves. The prevalence of pulmonic regurgitation increased significantly with age (p less than 0.0001), whereas the prevalence of mitral, tricuspid, and bivalvular regurgitation did not change with age. Valvular regurgitation was trivial or mild in 87% of patients. Thus mild valvular regurgitation is commonly found in children with structurally normal hearts.