The invention refers to a trailer coupling (10) for a towing vehicle (26), comprising a base body (12), a coupling unit (14) with a coupling element (16), that works with a counter-coupling element (18) of a trailing towing vehicle (22), whereby the coupling unit (14) relative to the base body (12) is adjusted between a coupling position and a release position, and a securing device (40), with a securing element (42), that can be adjusted between a securing position and a release position, whereby, in its securing position, it secures the coupling unit (14) in its coupling position. According to the invention, the securing element (42), in its release position, allows a transfer of the coupling unit (14) from its coupling position into its release position, and if the securing element (42) is pivoted by the coupling unit (14) in the course of its movement from the release position and into a coupling preparatory position, and then goes, when the coupling unit (14) has reached the coupling position, by itself into the securing position.