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.Instrumento de inserción para un sistema intrauterino, que comprende un mango que tiene una abertura longitudinal en un primer extremo, donde dicha abertura tiene un eje longitudinal que es paralelo al eje longitudinal del instrumento de inserción y comprende un primer extremo y un segundo extremo, una corredera desplazable que está localizada en dicha abertura longitudinal y que comprende un primer extremo y un segundo extremo, un émbolo móvil, un tubo de inserción localizado alrededor del émbolo, que comprende un primer extremo y un segundo extremo, donde el segundo extremo está unido a la corredera, un medio de fijación para fijar de manera reversible el sis
