Three series (series A-C) of coumarin analogues with phenylpiperazine functions as substitution were designed and synthesized for studying their potential for treating Alzheimer's (AD) disease. Their anticholinesterase activities were assayed according to Ellmann's method against freshly prepared acetylcholinesterase (AChE) from Electrophorus electricus using donepezil as the reference compound. Pharmacological study and preliminary structure-activity relationships showed that coumarins with substitution on positions 3 and/or 4 have parallel anti-AchE activities compared with the reference compound.