Current density maps are computed at the ipsocentric CTOCD-DZ/6-31G**//RHF/6-31G** level for angle-constrained planar 1,3,5,7-cyclooctatetraenes (COT) and benzene. Constraint of alpha(CCH) angles to 90degrees in D-4h COT (3b) leads to endo-4 and exo-4 valence isomers. The exo structure, with CH bonds perpendicular to long sides of the octagon, is lower in energy by 202 kJ/mol and has stronger bond alternation (DeltaR 0.265 Angstrom). However, endo-4, exo-4 and COT 3b at its best planar geometry all sustain intense paratropic ring currents, attributed to the rotational character of the HOMO-LUMO transition, and consistent, mutatis mutandis, with the diatropic current in D-3h benzene 5. (C) 2002 Elsevier Science B.V. All rights reserved.