We determined whether aortic prosthesis size influences survival and hemodynamic function. Eighty-nine patients who underwent small aortic valve replacement were followed. The small internal orifice area index (IOAI) group was defined as having an internal orifice area/body surface area ratio of < or = 1.3 cm(2)/m(2) (n = 34). The control group was defined as having an IOAI >1.3 cm(2)/m(2) (n = 55). The actuarial survival rate at 10 years was 74.5% in the small IOAI group and 75% in the control group (NS). Freedom from valve-related impairment at 10 years was 87% in the small IOAI group and 85% in the control group (NS). Postoperative pressure gradients were higher in the small IOAI group (p < 0.05). Left ventricular mass index decreased in both groups (albeit nonsignificantly in the small group, but significantly decreased in the control group). The long-term results of aortic valve replacement for patients with small aortic annulus were satisfactory. However, the postoperative pressure gradient through the prosthesis and left ventricular hypertrophy remained at a high level in the small IOAI group.