The invention relates to an inserter for an intrauterine system, comprising a handle (3) having a longitudinal opening (8) at its first end, said opening (8) having a longitudinal axis parallel to the longitudinal axis of the inserter, a first end (8a) and a second end (8b), a movable slider (5) arranged in said longitudinal opening (8) and having a first end (5a) and a second end (5b), a plunger (2) attached to the handle (3), an insertion tube (6) arranged around the plunger (2) having a first end and a second end, with its second end attached to the slider (5), wherein the inserter further comprises locking means for reversibly locking the intrauterine system in relation to the plunger (2) via a removal string of the intrauterine system, said locking means being controllable by the slider (5) and/or the insertion tube (6).