Device for inserting several bits in a rhythmed digital train, comprising aosed looped shift register, the shift being controlled according to the rhythm of the train. The register receives, in parallel, the bits to be inserted, the write-in locations depending on the instant at which it is required to have these bits available in order to insert them in the train. Preferably, the train being subdivided into sub-groups (IT) of adjacent bits, the register comprises as many bistable elements as there are bits in a sub-group.