The di-tert-butyl nitroxide (DTBN) hyperfine tensors are computed in a reasonable time frame using the UB1LYP method and Barone's electron paramagnetic resonance EPR-III basis sets. The effects of six solvents on the N-14 hyperfine splittings are calculated using the polarizable continuum method and reproduce the experimental trends. Further improvement in the accuracy is obtained when one extra water molecule is made to interact with the NO moiety. All the DTBN atoms are not magnetically equivalent since the molecule has C, symmetry. This must be taken into consideration when simulating the EPR line shapes of randomly oriented DTBN molecules isolated in an argon matrix.