A valve retainer is connected to an elongate delivery member. The valve retainer is configured to releasably secure a prosthesis (e.g., a heart valve prosthesis) to the delivery member during delivery to a target site in a body (e.g., a native valve annulus). The valve retainer includes a rotational identifier that identifies the rotational orientation of the valve retainer when the valve retainer is positioned proximate to the target site. A heart valve prosthesis can include a commissural post that has a predetermined rotational position relative to the rotational identifier, such that the heart valve prosthesis can be rotationally aligned with the native commissures of the native valve by rotating the delivery member and the valve retainer until the commissural post is aligned with a native valve commissure and the rotational identifier is visible.
