Abstract: The heart valve prosthesis comprises a substantially annular valve body having leaflets pivotally mounted to the valve body to be pivotable between respective open positions, in which blood is permitted to pass through the valve, and respective closed positions in which blood flow through the valve is substantially inhibited. The valve body is constructed of at least two part-annular elements and each respective leaflet is provided with at least two spaced pivot formations, each arranged to engage with a respective complementary pivot formation provided on a different part annular element. The annular body is assembled from the sub-elements and secured around the leaflets to provide a rigid annular body without the need for deformation or deflection of the annular body on assembly.