A coupling device for securing medical instruments to a holding device allows for simple and rapid handling and exact positioning of the medical instrument. A coupler socket is configured on one component and a coupler plug is configured on the other component, wherein the coupler socket and coupler plug can be fixed in mutually connected position with respect to one another by means of at least one locking element. The coupler socket is configured as a sleeve-shaped collet chuck comprising several mutually distanced spring arms. The coupler plug comprises a coupling pin equipped with at least one radially outward-pointing catch cam. When coupled, at least one catch cam of the coupling pin catches on a corresponding back-cut on the collet chuck. The locking element can be screwed onto the collet chuck so that the spring arms of the collet chuck in the coupled position are affixed facing radially outward.