The sizing of aortic valve (AV) homografts for optimum function requires an accurate measurement of the aortic annulus. Typically, this measurement is obtained directly with sizers in the open aorta. We describe the use of intraoperative transesophageal echocardiography (IOTEE) to measure the aortic annulus and select the appropriate AV homograft before cardiopulmonary bypass and aortic cross-clamping. Thirty-two patients underwent AV homograft insertion between March 1993 and March 1996 and had IOTEE. There were 13 women and 19 men. Mean age was 58 +/- 14 years. IOTEE measurements were satisfactory in sizing in all patients, and no extraordinary surgical measures were necessary to insert the AV homografts. Early postoperative follow-up showed trivial or mild regurgitation of all homografts. Prebypass IOTEE is reliable in guiding the selection of optimal AV homografts.