Semi-empirical molecular orbital treatment at the level of AMI unrestricted Hartree-Fock type calculations was performed on the Huckel type boron and nitrogen substituted cyclacenes. Substitution is done either in a peri position or a fusion points. Boron substitution is found to be destabilizing. whereas nitrogen substitution has stabilizing effect on parent cyclacenes. (C) 2003 Elsevier B.V. All rights reserved.