Abstract: The grooved shaft preferably has one or more axial grooves with semi-elliptical or U-shaped groove cross sections. Flat areas adjoin the axial groove or grooves. The flat areas are tapered tangentially relative to a substantially cylindrical shaft area. The grooved shaft optimally has a front shaft radius and a rear shaft radius. The front shaft radius is smaller than the rear shaft radius such that the front shaft radius may be oriented near an impeller intake to decrease hydraulic flow resistance. In practice, the grooved shaft is incorporated into a magnetic-drive centrifugal pump and the grooves are statically oriented in a position of minimal radial loading.