A piston pump is configured to convey pressure medium in a pressure medium circuit, in particular in a braking circuit of a motor vehicle braking system that may be electronically controlled to counteract slip. The pump piston delimits an operating chamber and is received in a displaceable manner in a pump cylinder and may be driven to produce a stroke movement that goes back and forth between two reversing positions. The operating chamber may be connected in a controllable manner to a pump inlet or outlet. A pressure medium connection is provided from the pump outlet to the operating chamber, said pressure medium connection is controllable in dependence upon a relative position of the pump piston with respect to the first reversing position. Pressure pulsations of the piston pump are prevented and the operating noise is reduced.