Abstract: An integrated centrifugal pump and motor is provided by an impeller disk which contains permanent magnets and functions as the rotor for a brushless DC motor. The rotor is supported by non-contacting radial bearings and is hydrodynamically balanced against any axial thrust so that there is no contact between rotating and stationary elements during operation. Since the impeller disk is also the motor rotor, there is no need for a shaft, in the ordinary sense, which would penetrate the case and, thus, require seals. The resulting pump is compact and can be operated electronically at variable speeds.