Intermittent aortic regurgitation is an unusual complication following a mechanical prosthesis replacement in the early postoperative period. Arterial pressure recording and echocardiographic assessment were enough to diagnose the prosthetic dysfunction. Reexploration of the valve confirmed the dysfunction, which was caused by a pannus of previous aortic valve replacement with the pulmonary valve. The pannus impeded normal closure of the leaflet in an intermittent way during diastole. Reorientation of the valve corrected the aortic insufficiency. Doppler ultrasound was a very useful noninvasive technique in order to evaluate the suspected prosthetic valve dysfunction in the immediate postoperative period.