The present invention relates to an inserter for an intrauterine system, comprising a handle (3) having a longitudinal opening (8) at its first end, said opening having a longitudinal axis parallel to the longitudinal axis of the inserter, a first end and a second end, a movable slider (5) arranged in said longitudinal opening and having a first end and a second end, a movable plunger (2), an insertion tube (6) arranged around the plunger having a first end and a second end, with its second end attached to the slider, locking means for reversibly locking the intrauterine system in relation to the plunger via a removal string of the intrauterine system, said locking means being attached to the plunger and being controllable at least by a part or an extension of the slider and/or of the insertion tube or of the handle. A typical inserter according to this invention further comprises movement means (18), which comprise a rotation part (19) arranged to rotate around a rotation axis that is perpendicular to the longitudinal axis of the inserter, the rotation part being arranged in functional connection with the plunger and with the slider, such that the movement of the slider generates simultaneous movement of the plunger and of the insertion tube along the longitudinal axis of the inserter, in opposite directions.La présente invention se rapporte à un instrument d'introduction destiné à un système intra-utérin, comprenant un manche (3) ayant une ouverture longitudinale (8) au niveau de sa première extrémité, ladite ouverture ayant un axe longitudinal parallèle à l'axe longitudinal de l'instrument d'introduction, une première extrémité et une seconde extrémité, un coulisseau mobile (5) placé dans ladite ouverture longitudinale et ayant une première extrémité et une seconde extrémité, un piston mobile (2), un tube d'introduction (6) agencé autour du piston ayant une première extrémité et une seconde extrémité, sa seconde extrémité étant attachée au coulisseau, et un moyen
