[en] The Zeeman splitting for conduction electrons in d-metals such as vanadium, niobium, tantalum is studied theoretically by the RLMTO method. The results are presented, which were obtained from calculation and averaging of g-factors, from the analysis of their stability against variations of the number of states and from calculation of the Zeeman level splitting enhancement due to the electron-electron interaction. The orbit averaged g-factors are found to dislplay the anisotropic behaviour on 02 sheet of the Fermi surface in these metals. The calculated results are compared with experimental one and those obtained by other authors. Common trendes of the g-factor behaviour are formulated for all transition d-metals with cubic structure