An atrioventricular heart valve prosthesis for replacing a native atrioventricular valve of a heart, the native valve having a native atrioventricular valve orifice, said prosthesis comprising a housing component and a valve component; wherein said housing component comprises: a housing body having a housing passage extending therethrough; said housing body being configured to be located in, or adjacent to and communicating with, the native valve orifice of the heart; and an anchoring mechanism secured to said housing body and configured to engage tissue of the heart; said housing component being configurable between a housing collapsed state for delivery to the native valve orifice via catheter and a housing expanded state to engage said anchoring mechanism with the tissue of the heart to fix said housing body in relation to the native valve orifice; further wherein said valve component comprises: a valve body having a valve passage extending therethrough; said valve body being configured to be located at least partially within said housing passage with said valve passage extending along said housing passage; and one or more flexible valve elements secured to said valve body and extending across said valve passage for blocking blood flow in a first direction through said valve passage whilst allowing blood flow in an opposing second direction through said valve passage; said valve component being configurable between a valve collapsed state for delivery to said housing passage via catheter, when said housing body is in said housing expanded state following delivery to the native valve orifice, and a valve expanded state to engage said housing component and/or structure of the heart to fix said valve body at least partially within said housing passage; wherein said anchoring mechanism includes a plurality of ventricular prongs secured to and spaced about said housing body, said ventricular prongs each secured to said housing body by one or more legs extending from a ventricular end of said housing body into a ventricle of the heart communicating with the native atrioventricular valve orifice. a housing body having a housing passage extending therethrough; said housing body being configured to be located in, or adjacent to and communicating with, the native valve orifice of the heart; and an anchoring mechanism secured to said housing body and configured to engage tissue of the heart; said housing component being configurable between a housing collapsed state for delivery to the native valve orifice via catheter and a housing expanded state to engage said anchoring mechanism with the tissue of the heart to fix said housing body in relation to the native valve orifice; further wherein said valve component comprises: a valve body having a valve passage extending therethrough; said valve body being configured to be located at least partially within said housing passage with said valve passage extending along said housing passage; and one or more flexible valve elements secured to said valve body and extending across said valve passage for blocking blood flow in a first direction through said valve passage whilst allowing blood flow in an opposing second direction through said valve passage; said valve component being configurable between a valve collapsed state for delivery to said housing passage via catheter, when said housing body is in said housing expanded state following delivery to the native valve orifice, and a valve expanded state to engage said housing component and/or structure of the heart to fix said valve body at least partially within said housing passage; wherein said anchoring mechanism includes a plurality of ventricular prongs secured to and spaced about said housing body, said ventricular prongs each secured to said housing body by one or more legs extending from a ventricular end of said housing body into a ventricle of the heart communicating with the native atrioventricular valve orifice. a valve body having a valve passage extending therethrough; said valve body being configured to be located at least partially within said housing passage with said valve passage extending along said housing passage; and one or more flexible valve elements secured to said valve body and extending across said valve passage for blocking blood flow in a first direction through said valve passage whilst allowing blood flow in an opposing second direction through said valve passage; said valve component being configurable between a valve collapsed state for delivery to said housing passage via catheter, when said housing body is in said housing expanded state following delivery to the native valve orifice, and a valve expanded state to engage said housing component and/or structure of the heart to fix said valve body at least partially within said housing passage; wherein said anchoring mechanism includes a plurality of ventricular prongs secured to and spaced about said housing body, said ventricular prongs each secured to said housing body by one or more legs extending from a ventricular end of said housing body into a ventricle of the heart communicating with the native atrioventricular valve orifice.