One hundred consecutive aortograms, performed with careful attention to recommended technical details, were reviewed to identify cases of "factitious" aortic valve insufficiency, viz. aortic regurgitation seen during aortography for which there is no clinical evidence. Five patients with this condition were identified. Two of these subsequently underwent mitral valve replacement under cardiopulmonary by-pass. Aortic insufficiency was not detected during this procedure and the aortic valve appeared to be anatomically normal at postmortem examination. That factitious aortic insufficiency may exist should be remembered when aortography is used to differentiate aortic from pulmonary valve insufficiency.