Abstract: The invention relates to a pump unit (10) for a hydraulic vehicle brake system with traction control. The pump unit (10) has an electric motor (12) and a radial piston pump (14), which can be driven by the electric motor (12). The invention proposes embodying a rotor shaft (18) of the pump unit (10) with a hollow shaft (20) and with two standardized, hardened cylindrical pins (22, 24) that are press-fitted into the ends of the hollow shaft (20). The invention has the advantage that the rotor shaft (18) can be produced simply, economically, and without metal-cutting machining. Because of its embodiment as a hollow shaft (20), the rotor shaft (18) has high bending and torsional strength. Because of the press-fitted pins (22, 24), the rotor shaft (18) has a small diameter at the bearing points, which makes a small bearing diameter and thus a small installation space for the pump unit (10) possible.