Using an all-electron mixed-basis approach and within the local-density approximation, the electronic structure of C58BN heterofullerenes in the solid fcc phase (F3»m) has been calculated. We study the two cases where the boron and nitrogen atoms are neighbors and where they are located far apart. The effect of this substitutional doping, which is expected to create acceptor and donor levels in the gap, is investigated and the electron dispersion relations are calculated in both cases. We find that when N and B are neighbors the donor and acceptor levels are pushed into the continuum, and we deduce that this configuration is slightly more stable than the one in which they are far apart. Total and partial charge densities of the occupied bands are displayed. From the present study, we have concluded that there is a single bond between N and B when they are neighbors, and the additional two electrons are mostly localized around N, and therefore only a small relaxation of the atoms is expected.