Abstract: A device for positioning the end of an optical fibre (1) in a sleeve (10) includes at least three mutually parallel rods (2, 3, 4, 5) forming a passage between themselves for accommodating the fibre end, one end of the rods being intended for insertion into the sleeve (10). Each rod has two flat surfaces intersecting each other at a long edge, one flat surface of each rod lying against a flat surface of an adjacent rod such that the long edges of the rods extend parallel to, and are distributed around the symmetrical axis of the passage. The rods are mutually displaceable in relation to the symmetrical axis, while the engaging surfaces slide on each other for changing the size of the passage to suit different fibre diameters. The ends of the rods intended for insertion in the sleeve have a third flat surface (11, 12, 13, 14) forming equal angles with the two flat surfaces of the respective rod which is intended to engage against a complemental flat surface in the sleeve (10).