The motor/pump unit (10) comprises an electromotor (12) and at least one pump (14) for delivering brake fluid. The electromotor (12) has a motor stator (16) in which a motor rotor (18) is rotatably disposed. The pump (14) is disposed substantially within the motor rotor (18) and can be driven by the latter. In order to provide a vehicle brake system with a motor/pump unit (10) which is capable of delivering brake fluid in a highly dynamic fashion, the motor stator (16) and at least one section (22) of the motor rotor (18) which is directed towards the motor stator (16) define an electromagnetic region (16, 22, 24), and at least the pump (14) defines a hydraulic region (14, 26), wherein at least one sealing element (28, 96, 98) is provided which separates the electromagnetic region (16, 22, 24) from the hydraulic region (14, 26) in a fluid-tight fashion.