The aim of this study was to evaluate midterm echocardiographic results and changes in quality of life after aortic valve replacement with 17-mm St. Jude Medical Regent mechanical prostheses in patients with aortic valve stenosis. The study population was 34 women and 2 men, aged 31-83 years. Echocardiographic follow-up was 100% complete at 4.1 +/- 1.8 years. Hospital mortality was 5.6%. Actuarial 5-year survival was 88.5% +/- 0.067%. Postoperative echocardiography showed significant regression of left ventricular mass index and significant reductions of peak gradient, mean gradient and mean effective orifice area index. All survivors were interviewed using the 36-item Short Form Health Survey questionnaire. Scores obtained in 7 of the 8 domains of the test were significantly higher than preoperative values. In our experience, implantation of this prosthesis allowed regression of left ventricular mass index and improved the perceived quality of life.