Radial velocities of 570 B stars, mostly fainter than apparent magnitude 7 · 5 of spectral types between O8 and B5, have recently been determined at Victoria (Petrie and Pearce 1962). Spectroscopic absolute magnitudes based upon the measured strength of Hγ absorption have been determined for these stars. In addition to this totally new material, spectroscopic absolute magnitudes have been measured for an additional 180 stars. From the two lists 490 stars are available for a study of their distributions and radial velocities, since for this number magnitudes and colours have been measured with sufficient precision to allow reliable estimates of the interstellar extinction and the true distance moduli. The results given here are preliminary in the sense that approximately 200 additional stars will be added to the study when the program to determine photoelectric magnitudes and colours is completed. The radial velocities and absolute magnitudes of all the stars have already been measured.