Abstract: Breast pump with a suction funnel (2) for resting against a breast, which suction funnel is connected to a pump unit in the form of a flexible receptacle (4) which after compressing and releasing generates a negative pressure in the suction funnel (2) creating a pump action. The suction funnel and the flexible receptacle (4) being connected with a connector part (3). It comprises a release valve (11) at or in the connector part (3), which is provided to release air from the flexible receptacle (4) when this is compressed, the flexible receptacle being bottleshaped.