The methanol extracts of 340 kinds of Korean medicinal herbs were examined in vitro for the inhibitory effect on the acetylcholinesterase (AChE, E.C. 3.1.1.7) from electric eel using acetylthiocholine as a substrate. Among tested, the extracts of Coptidis Rhizoma, Phellodendri Cortex, Evodiae Fructus, Myrrha, Arecae Semen and Piperis nigri Fructus were found to exhibit a significant inhibition upon the acetylcholinesterase in a dose dependent manner, respectively.