We report on 254 consecutive patients (170 male, 84 female) undergoing aortic valve replacement with the Toronto SPV Stentless Valve (St. Jude Medical, Inc., St, Paul, Minn,), Mean age (+/- standard deviation) was 62.1 +/- 11.6 years, Three patients (1%) received sizes 21 or 22 mm, 24 (9%) received size 23 mm, and 227 patients (89%) received sizes 25, 27, or 29 mm, Serial echocardiography was used to assess valve performance during a 3-year follow-up, Mean gradient decreased by 35.8% (p < 0.0001; 95% confidence interval -39.6%, -31.7%) from postoperative values to the 3- to 6-month follow-up and by 6.1% (p = 0.004; 95% confidence interval -10.1%, -2%) at each subsequent interval; effective orifice area increased by 17.2% (p = 0.0001; 95% confidence interval 12.0%, 22.6%) initially and by 4.4% (p < 0.001; 95% confidence interval 1.8%, 7.0%) thereafter, At 2 years of followup, mean gradient was 3.3 +/- 2.1 mm Hg and mean effective orifice area was 2.2 +/- 0.8 cm(2). Studies on left ventricular mass were carried out on 84 patients, Left ventricular mass decreased by 14.3% (37.8 +/- 57.9 gm; p < 0.0001; 95% confidence interval -53.7, -21.9 gm) and left ventricular mass index decreased by 15.2% (21.1 +/- 30.5 gm/m(2); p < 0.0001; 95% confidence interval -29.5, -12.7 gm/m(2)) from postoperative values to the 3- to 6-month follow-up interval, The reduction in residual gradient and potential regression in left ventricular hypertrophy may have a beneficial prognostic implication, We believe that the unique stentless design of the Toronto SPV Stentless Valve allows this to occur.