Abstract: In an instrument for inserting a suppository, which instrument comprises a tubular housing (31) with a first end adapted to receive said suppository between two tongues (30) and a second end through which a plunger (22) is inserted in the tube, which plunger has a first end having a circular cross section and two axially spaced circumferential flanges (26, 27) and a second end projecting from the second end of the tube (31). The first end of the tube has an inwardly extending shoulder (25) which engage between said flanges (26, 27) and the first end of the piston is by radial slots divided into an uneven number of sectors (29). The plunger (22) has between its first end and a press button (24) at its second end angular spaced radial walls (21) abutting the inner wall of the tube (31) and axial spaced disc shaped walls are provided having a diameter corresponding to the inner diameter of the tube (31).