Considerable experimental evidence suggests that phenserine and some alkyl analogues show inhibitory action against human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The electronic structure of the newly synthesised anti-ChE compounds 1-7 have been studied by using ab initio methods at the correlation level. The most probable structures of the systems under consideration have been determined being in a good agreement with the relevant experimental results. The geometries showed that 2' substitution on to the phenyl ring of the carbamate function cause its rotation to the rest of the molecules. These structures are more selective and potent inhibitor against AChE. (C) 2004 Elsevier B.V. All rights reserved.