A device includes a tubular endoprosthesis (11) and a hollow prop (13) provided in the vicinity of a distal end with at least one transverse retaining opening (23A). The device includes a releasable retaining member (31). It also includes filamentary line (33A) which forms an eyelet (41) around the retaining member (31), and a tightening loop (43) around the endoprosthesis (11), and which includes traction means (45) extending the tightening loop (43). The traction means (45) extend at least as far as a control end in the vicinity of a proximal and of the prop (13) and can be moved relative to the prop (13) towards the distal end of the prop (13) to a position in which the endoprosthesis (11) is in an expanded state. The invention is applicable to releasing endoprostheses in a blood vessel.
