Possible structures of heterofullerenes C60-xNx and C60-xBx (x = 2-8) have been calculated using semiempirical MNDO, AM1, PM3, and ab initio methods in order to determine the most stable structures, to investigate the underlying cause of their stabilities, and to predict their electronic properties. The calculation results indicate that the N-doped fullerenes are more stable than their B-doped analogues, but both are less stable than C-60 thermodynamically, and the stabilities decrease with increasing number of the heteroatoms. The most likely structures of the heterofullerenes investigated in this paper are determined; it is found that there is a fair correlation between the regioisomerism of N- or B-doped fullerenes and that of fullerene adducts. It is proposed that the changes of hybridization from sp(2) to sp(3) are the predominant factors of the regiochemistry for both heterofullerenes and fullerene adducts, which leads to the existence of this unexpected correlation. This regioisomerism correlation makes it possible to deduce the most stable structures of heterofullerenes on the basis of the relatively well studied fullerene adducts. The redox characteristics of fullerene C-60 can be enhanced by doping; heterofullerenes under investigation have somewhat smaller ionization potentials and bigger affinity energies relative to their all-carbon analogue C-60, which suggests it is easier to oxidize and reduce these doped fullerenes relative to C-60 There should be significant electron transfer when the dimeric fullerenes are formed, and these electron-transfer directions are predicted.