Stentless valvular bioprostheses have been used clinically for over 8 years and the excellent properties of the bioprostheses have been demonstrated in clinical studies. The present study examined how differing elastic conditions around the bioprosthesis at the aortic position affect the hydrodynamic characteristics of the bioprosthesis. Bioprosthesis implantation is typically performed using either the subcoronary or the full-root technique. These procedures for implanting a stentless prosthetic heart valve at the aortic root were hydrodynamically evaluated in a mock circulatory system. Forward flow rate was 11% greater with the subcoronary technique than with the full-root technique. In a high-speed video camera study, the orifice area at full opening was 12% larger for the subcoronary technique than for the full-root technique. Evaluation of bioprosthetic characteristics in terms of mechanical conditions is important when considering surgical options.