A prosthesis for the partial replacement of a vertebral body includes an upper contact plate for connection to an upper vertebral body, a lower contact plate for connection to a lower vertebral body and a bridging part which connects the upper and lower contact plates to one another and bridges at least one intermediate vertebral body which is located between the upper and lower vertebral bodies and is to be partially replaced. The bridging part is accommodated in a recess in the vertebral body and is secured in the recess with lateral anchoring projections which penetrate into the bone substance located on both sides of the bridging part. The cross section of the bridging part may narrow toward the rear, preferably in a trapezoid shape.