An ab initio study has been performed, at both the UHF and UMP2 levels, of the conformational dependence of j3 hyperfine coupling constants of the dimethyl nitroxide radical. This compound has been chosen as a model of the nitroxide series, and relations between the conformations of j3 hydrogens and the out-of-plane deviations of the NO group have been derived. It is thus possible to construct an abacus allowing an easy interpretation of the ESR spectra of such compounds, which confirms the results of a previous semiempirical study. In addition, correlation effects on j3 spin densities are shown to follow the same dependence as that reported for delocalization and spin polarization.