Abstract: Device for pneumatically milking a cow, including a number of milk extractors, each having a teat cup as well as a milk line connected to the lower end of the teat cup, which leads from the teat cup to a collection chamber for the milk from the teat cups. Each milk extractor is provided with a supply for a cleansing medium, such as a disinfectant, to the teat cup in particular to the teat present in the teat cup. The supply has a line which at the location of an outlet debouches into the milk extractor, in particular the milk line, and each milk extractor is provided with structure for closing off the milk extractor near or downstream of the outlet when discharging the cleansing medium through the outlet. The structure for closing off the milk extractor is preferably arranged near the transition of the teat cup to the milk line.