Abstract: The invention is directed to an adaptor for releasably attaching a sighting telescope to a weapon. The adaptor includes an elongated base body having upper and lower sides with a holder formed on the upper side for holding the sighting telescope therein. A rigid fixing element is formed on the lower surface of the base body for engaging the weapon at a first location thereon and a movable fixing element releasably engages the weapon at a second location thereon. The adaptor affords the advantage that a tedious alignment of both fixing elements with respect to each other is eliminated when mounting the adaptor on the weapon. A later misalignment of the two fixing elements to each other is no longer possible since they are both disposed on one and the same base body.