Essential oils have the potency to inhibit acetylcholinesterase (AChE). In our study, 29 essential oils from aromatic plants were screened for cholinesterase inhibitory activity using Ellman's colorimetric method. Results revealed that the essential oils from Eucalyptus, Cajuput, Sweet magoram, Camphor tree and Rosemarry showed such activity. The compositions of these essential oils were analyzed by GC-MS. We also demonstrated that the AChE inhibitory activity of the essential oil could be attributed to 1,8-cineole.