The CarboMedics ‘Top-Hat’ prosthesis has been designed for supra-annular aortic implantation. We present the results of the first five years of our clinical studies, including 128 patients undergoing aortic valve replacement with this mechanical prosthesis. Mean follow up was 24.8 months per patient. Overall mortality rate was 1.5% (two deaths). The safety of implantation was good, and short-term clinical outcome was considered satisfactory.