The possible stable structures of substituted fullerenes C_(34)BN formed on the initial C_(36) cages of D_(6h) and D_(2d) symmetries have been systematically investigated at the AM1 and MNDO levels. The relationship between the stabilities of the C_(34)BN isomers and the sites where boron or nitrogen atoms dope at the C_(36) cage has been discussed. The results show that for the C_(36) cage with D_(6h) symmetry, the most stable isomer of C_(34)BN derivative is formed by boron and nitrogen atoms doping at the 1,4-sites in the six-membered ring which locates at the equatorial belt of C_(36) belt of C_(36) cage. While for C_(36) cage with D_(2d) symmetry, the most stable isomer of C_(34)BN derivative is formed by boron and nitrogen atoms doping at the sites near equatorial belt of C_(36) cage, which corresponds to 1,2-substitution pattern. It seems that the stabilities of C_(34)BN isomers are mainly determined by the conjugate effect of the cage. The activity of the redox of the C_(34)XY (X, Y = B, N) isomers increases in the following order: C_(34)B_2

Key words: C36, STABILITY, ELECTRONIC STRUCTURE, FRONTIER ORBITAL THEORY