The Huckel type cycled-fused-borazines which are analogous to cyclacenes are considered for the semiempirical molecular orbital treatment at the level of MNDO and AMI type calculations. The structures having 3-10 arenoid rings (R) are considered. It has been found that they should be thermally stable and exogenic. Moreover, these properties get more and more as R increases. The systems exhibit no cryptoannulenic effect on any of the properties presently studied, showing that the peripheral circuits, unlike the ones in cyclacenes, are not influential. (C) 2003 Elsevier B.V. All rights reserved.