Abstract: A device for expressing milk from one or more breasts has at least one, and preferably two expressers and a pump. The expressers each have a cup for fitting on the breasts and a cup outlet to which a vacuum created by the pump can be connected. The cups have a flexible liner which collapses around the breast to establish the vacuum. Pulsating pressure is applied to the outside of the liner to increase the vacuum and stimulate milk production. The pressure is applied through lines which are vented to maintain adequate, consistent pressure pulses without stalling the pump.