Abstract: An eccentric bearing for an electrohydraulic piston pump assembly of a vehicle brake system includes a shaft which can be driven in rotation about its axis, a bearing ring which is eccentric relative to the shaft, and rolling bodies arranged between the bearing ring and the shaft. The rolling bodies have different diameters corresponding to a varying width of a gap between the bearing ring and the shaft. When the shaft is driven in rotation, an eccentricity of the bearing ring circulates around the shaft at half of the rotational speed of the shaft and drives pump pistons. The pump pistons bear at the outside against the bearing ring so as to perform a reciprocating movement.