A milking parlour cleaning system which cleans only part of the milking stall milk lines at a time is disclosed. This allows a voluntary milking system to always have stalls available to the animals wanting to be milked. A method of cleaning is also disclosed. The milking parlour comprises a annular rotary platform (2) and a plurality of milking stalls (3a, 3b) arranged on the platform (2). A first milk line system conducting milk from a first group of milking stalls (3a) on the platform and a second milk line system conducting milk from a second group of milking stalls (3b) on the platform (2) are connected to a common collection tank. The first milk line system and the second milk line system are separate milk line systems. The rotary milking parlour comprises a washing device capable of performing a washing process of one of said milk line systems at a time, and a blocking system (11, 15a) preventing animals from entering the group of milking stalls (3a, 3b) in which the milk line system is currently being washed and allowing animals to enter and be milked in the group of milking stalls (3a, 3b) in which the milk line system is not currently being washed.
