In order to improve an implant for the replacement of at least a part of a natural articular surface of a bone forming part of a joint comprising an anchorage surface abutting against the remaining bone and an artificial articular surface directed away from the bone in such a way that as little bone substance as possible should be removed in a simple manner for insertion of the implant, it is proposed that the anchorage surface comprises at least one cylindrically shaped area, which defines a cylinder axis.