An assembly for loading a self-expanding prosthetic heart valve into a delivery device, comprising: a compression member having a first open end with a first diameter, a second open end with a second diameter less than the first diameter, and a wall decreasing in diameter from the first open end to the second open end, the wall defining an open space adapted to receive the heart valve; a support member having a base on a first end and a recess on a second end, the recess having a fixed depth between a support surface of the recess and an open end of the recess, the recess being adapted to receive an end of the heart valve, the support member and the compression member being movable relative to one another between an initial position in which the base of the support member is relatively far from the first open end of the compression member and an operative position in which the base of the support member is relatively close to the first open end of the compression member, wherein movement of the support member and the compression member from the initial position to the operative position pushes the heart valve through the open space such that the heart valve is radially compressed by the tapered wall of the compression member as the heart valve advances through the open space; a constricting member having a first end and a second end, the second end of the constricting member being sized to receive the compressed heart valve from the second open end of the compression member; characterised in that it further comprises a spacer adapted for assembly in the recess so that the recess has a depth between a support surface of the spacer and the open end of the recess which is less than the fixed depth. a compression member having a first open end with a first diameter, a second open end with a second diameter less than the first diameter, and a wall decreasing in diameter from the first open end to the second open end, the wall defining an open space adapted to receive the heart valve; a support member having a base on a first end and a recess on a second end, the recess having a fixed depth between a support surface of the recess and an open end of the recess, the recess being adapted to receive an end of the heart valve, the support member and the compression member being movable relative to one another between an initial position in which the base of the support member is relatively far from the first open end of the compression member and an operative position in which the base of the support member is relatively close to the first open end of the compression member, wherein movement of the support member and the compression member from the initial position to the operative position pushes the heart valve through the open space such that the heart valve is radially compressed by the tapered wall of the compression member as the heart valve advances through the open space; a constricting member having a first end and a second end, the second end of the constricting member being sized to receive the compressed heart valve from the second open end of the compression member; characterised in that it further comprises a spacer adapted for assembly in the recess so that the recess has a depth between a support surface of the spacer and the open end of the recess which is less than the fixed depth.