Ab initio calculations on the nonplanarity of adducts with spin traps H-N=0, CH3-N=0, and CH3-CH2-N=0 indicate that the degree of nonplanarity at the N correlates weakly with the electronegativity of the adding radical. The degree of nonplanarity depends on the level of theory used : extending the basis set beyond the 6-31G(d) level within the Hartree-Fock framework reduces the nonplanarity slightly, and including the effects of electron correlation at the MP2/6-31G(d,p) level reduces it considerably more. However, the trends within a given theory level and basis set are essentially the same. Formation energies indicate that in general the adducts are strongly favored over the free radical and the spin trap.