SCF MO LCAO has been used in the CNDO/2 approximation to determine the valence states for borine and nitrogen in substituted phenazaborines containing 3-coordinated and 4-coordinated boron atoms. In the first case, the heterocyclic electron structure has donor-acceptor interaction for the heteroatom π orbitals via the π-electron system in the phenylene groups and substantial conjugation of the latter via the heteroatom π orbitals. In the second, those effects are much weaker and the heterocycle has a nonplanar structure. The valence index V_B(4) for the 4-coordinated B(4) does not exceed V_B(3).