An arrangement is provided in a rotary milking system comprising a rotating platform (1) which rotates during milking, an entry (2) thereto and an exit (3) from there. A selection gate arrangement (23) is provided at the exit of the rotating platform and is capable of selectively guide animals, which have been milked in the rotary milking system and leave the rotating platform through the exit, back to the entry of the rotating platform or to a waiting area (25). A control device (24) is provided for (i) determining whether an animal, which has been milked and leaves the rotating platform through the exit, has at least one udder compartment that was incompletely milked the last time the animal was milked, and (ii) controlling the selection gate arrangement to guide the animal back to the entry of the rotating platform or to the waiting area provided that the animal has at least one udder compartment that was incompletely milked the last time the animal was milked.
