Abstract: Plastic ball valve, with a spherical shut-off member which is provided with a passage and is rotatably accommodated in a cylindrical inner housing, and is coupled to a jack. The inner housing is accommodated in a cylindrical outer housing provided with two connection sockets. The shut-off member is retained in the inner housing by two annular retaining parts lying on either side of the shut-off member. Each retaining part is provided with one or more radially projecting and resilient hook ribs which are accommodated in a peripheral groove formed on the inside, and near one end of the inner housing. The outer housing consists of an essentially cylindrical intermediate housing to which an end flange of a cylindrical connection socket is fixed on either side.