A simple, reliable semiquantitative method for evaluating aortic valve insufficiency by means of cine MR is described. Ten normal persons and 36 patients with aortic valve abnormalities were examined in a 1.5 Tesla apparatus using ECG-triggered gradient echo sequences. The heart was imaged along its short axis. Semiquantitative evaluation of aortic valve insufficiency was calculated from an MRI index, which depends on the diameter of the aortic regurgitant jet and on its length; the results were compared with colour Doppler echocardiography and cardioangiography. The MRI index showed better correlation with cardioangiography (r = 0.92) than the correlation between the colour Doppler echocardiography and cardioangiography (r = 0.78). Over and under estimates are less common with MRI than with colour Doppler echocardiography. MRI showed very little interobserver variability (r = 0.96, p less than 0.001). Cine MR is a reliable method for demonstrating aortic valve insufficiency. Using the short axis of the heart, rapid semiquantitative evaluation of the aortic regurgitant jet is regularly possible.