This invention relates to an insert for fixation of a railway clip comprising an inner conduit, parallel to the rail, intended to receive the rectilinear central portion of the clip, a horizontal rear face on which abuts the rear portion, parallel to the rail, of the clip which is joined to the central portion by a 180.degree. bend and which then extends towards the rail, above the inner conduit, by a substantially perpendicular loop whose end comes into abutment on an insulating stop resting on the base of the rail, wherein the upper face of the insert comprises, towards the inlet orifice of the inner conduit, a retaining boss against which the loop of the clip comes into bearing contact to maintain the clip in a position of equilibrium, where the free end of the central portion is placed in the inlet orifice of the inner conduit.