OBJECTIVES: Heart valve replacement with a bioprosthesis is one of the most frequently performed procedures in cardiac surgery and represents a highly effective therapy to relieve diseased heart valves. Nevertheless, as postoperatively elevated transvalvular gradients and prosthesis-patient mismatch are reported as shortcomings of the procedure or of the currently used devices, there is a need for novel bioprostheses with improved haemodynamics. This study presents preclinical haemodynamic results after mitral valve replacement with the novel TRIBIO bioprosthesis (TRIBIO) compared with an established bioprosthesis in a sheep model. METHODS: Six female sheep had their mitral valves replaced with the TRIBIO and 3 with the Carpentier-Edwards Perimount, both sized 19 mm. The TRIBIO consists of a flexible valve-bearing crown, a force-decoupled interface and an intra-annular base ring. Mean and peak transvalvular gradients as well as an effective orifice area were monitored in both groups using transthoracic echocardiography over the course of the 90-day study. RESULTS: In both groups, haemodynamic performance diminished over time. The TRIBIO demonstrated overall superior haemodynamics, i.e. lower transvalvular gradients and a larger effective orifice area, although the results were not statistically significant. On Day 90, the mean values for the mean and peak transvalvular gradients and the effective orifice area were 6 mmHg, 10.2mmHg and 1.2 cm2 for the TRIBIO and 10 mmHg, 15.8mmHg and 0.8 cm2 for the Carpentier-Edwards Perimount, respectively. CONCLUSIONS: This study demonstrates a trend towards improved preclinical haemodynamic performance following mitral valve replacement with the TRIBIO compared to that with an established bioprosthesis in a sheep model.