Flow-encoded magnetic resonance (MR) sequences allow the quantitative evaluation of blood flow in any plane of the heart and vessels. For the first time, ejection and regurgitation volumes of the left ventricle in the ascending aorta can be measured noninvasively. Thus, the regurgitation fraction as a reliable measure of aortic valve insufficiency can be determined. The quantitative evaluation of aortic valve insufficiency was done by MR in comparison to ultrasound-Doppler and, in some cases, in comparison to heart catheterization. A good correlation of grading aortic valve insufficiency by the new MR-technique in comparison to clinical graduation is shown. The development of a new noninvasive standard for quantification of aortic valve insufficiency seems possible.