Colour flow mapping Doppler echocardiography is a new, noninvasive method for studying the direction and velocity of blood flow within the cardiac chambers. In order to estimate the sensitivity and specificity of this method in the evaluation of aortic regurgitation, 44 patients were examined consecutively. In 24 patients, aortic valve incompetence was proven by angiography; in 20 patients aortography revealed no regurgitation. Quantification of the severity of aortic insufficiency was performed by grading the amount of colour of the regurgitant flow (grade I-IV) and comparing it with the angiographic data. In 43 out of 44 patients diagnostic images could be obtained with colour flow mapping Doppler echocardiography. With this method aortic insufficiency was detected in all cases (sensitivity 100%). The specificity was 97% (one false positive diagnosis). For quantification of the severity of regurgitation agreement with the angiographic findings was obtained in 18 out of 24 cases. In the remaining 6 patients the difference was one grade. CONCLUSIONS Colour flow mapping Doppler echocardiography is an important advance in the noninvasive preoperative diagnostics of aortic incompetence.