The invention relates to a device for the distraction of bones or bone segments. The device comprises an anchoring screw having a longitudinal axis, a screw tip, a screw end for rotatably driving the anchoring screw, a threaded shank which adjoins the screw tip and has a screw thread, and a screw shank adjoining the screw end; and a distraction sleeve axially displaceable on the screw shank including a rear end, a front end, a through-bore extending coaxially therebetween, an external thread adjoining the front end, and a coupler portion formed in the rear end for receiving a driving tool. The anchoring screw comprises a collar positioned between the threaded shank and the screw shank that radially projects at least from the screw shank and which serves as an axial stop for the front end of the distraction sleeve when the distraction sleeve is positioned over the screw shank. The through-bore has a boring section with an enlarged cross-section which adjoins the rear end provided with a lateral surface and a seal ring coaxially arranged between the lateral surface and the screw shank.