The invention relates to a procedure as well as a device for introducing an endoprosthesis into the distal end of a catheter by means of which the endoprosthesis is introduced into a vessel for implantation therein and is released to undergo self expansion by moving the tip of a catheter axially relative to the distal end of an outer catheter. An embodiment of the proposed device comprises a hollow cylindrical housing designed to receive the endoprosthesis, a piston axially displaceable therein which can be brought into engagement with the endoprosthesis, and a nose section arranged at one end of the housing, said nose section being provided with a recess tapering in the direction of an opening, and by means of said recess the endoprosthesis supplied by the piston may be introduced, with compressed diameter and in elongated form, into the distal end of the catheter replaceably arranged on the nose section.