Although new models of bileaflet valves with improved orifice have been devised, aortic valve replacement with 19mm prostheses still raises concerns about long term effects of residual transprosthetic gradient. We reviewed our experience with 19 mm standard model St Jude prostheses in 68 patients operated on between January 1983 and December 1995. Clinical late assessment was performed to evaluate the incidence of valve related complications. Postoperative echocardiography was performed to evaluate hemodynamic performance of the prostheses. Mean body surface area was 1.66+/-0.14 m2. Late postoperative peak gradient was 53.85+/-7.16 mmHg; mean gradient was 34.80+/-5.55 mmHg; effective orifice area was 1.93+/-0.05 cm2. Thirteen-year actuarial survival has been 90.89+/-0.6%; thirteen-year freedom from embolism 89.41+/-0.7% and freedom from hemorrhage 98.25+/-0.02%. No case of prosthetic endocarditis, thrombosis, or reoperation was observed during follow-up.