Stent delivery system, comprising: - a handling device having a housing, a thumbwheel mounted in the housing to be rotatable, and a winding spool rotating together with the thumbwheel; - a catheter arrangement having an inner shaft, with a proximal end of the inner shaft fixed on the housing, an outer sheath disposed coaxially to the inner shaft, and having at least one stent which is received radially between the inner shaft and the outer sheath; - a flexible pull member which, with one end, engages on a proximal end of the outer sheath and, with the other end, is held on the winding spool to be windable; - wherein, for release of the at least one stent, the outer sheath is displaceable relative to the inner shaft in the proximal direction by means of winding the flexible pull member on the winding spool; characterized in that - a locking mechanism is provided and in operative connection to the thumbwheel, which locking mechanism causes, upon reaching at least one defined angle (α) of rotation of the thumbwheel, a locking state of the rotational mobility of the thumbwheel and thereby of the proximal displaceability of the outer sheath; and that - an unlocking mechanism is provided and in operative connection to the locking mechanism, by means of which unlocking mechanism the locking state is reversible, - characterized in that the locking mechanism includes a rotatably mounted driving gear which is driven by the thumbwheel, a rotatably mounted driven gear which is driven by the driving gear, and a movably mounted locking member on which the driven gear comes into abutment upon reaching the at least one defined angle (α) of rotation of the thumbwheel, thereby producing the locking state, wherein the locking member is displaceable relative to the driven gear by means of the unlocking mechanism for reversing the locking state. - a handling device having a housing, a thumbwheel mounted in the housing to be rotatable, and a winding spool rotating together with the thumbwheel; - a catheter arrangement having an inner shaft, with a proximal end of the inner shaft fixed on the housing, an outer sheath disposed coaxially to the inner shaft, and having at least one stent which is received radially between the inner shaft and the outer sheath; - a flexible pull member which, with one end, engages on a proximal end of the outer sheath and, with the other end, is held on the winding spool to be windable; - wherein, for release of the at least one stent, the outer sheath is displaceable relative to the inner shaft in the proximal direction by means of winding the flexible pull member on the winding spool; - a locking mechanism is provided and in operative connection to the thumbwheel, which locking mechanism causes, upon reaching at least one defined angle (α) of rotation of the thumbwheel, a locking state of the rotational mobility of the thumbwheel and thereby of the proximal displaceability of the outer sheath; and that - an unlocking mechanism is provided and in operative connection to the locking mechanism, by means of which unlocking mechanism the locking state is reversible, - characterized in that the locking mechanism includes a rotatably mounted driving gear which is driven by the thumbwheel, a rotatably mounted driven gear which is driven by the driving gear, and a movably mounted locking member on which the driven gear comes into abutment upon reaching the at least one defined angle (α) of rotation of the thumbwheel, thereby producing the locking state, wherein the locking member is displaceable relative to the driven gear by means of the unlocking mechanism for reversing the locking state.