In this study, some new 2-(4-substituted piperazine-1-yl)-N-[4-(2-methylthiazol-4-yl)phenyl]acetamide derivatives were synthesized. The synthesized compounds were screened for their anticholinesterase activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes by in vitro Ellman's method. The structural elucidation of the compounds was performed by using IR, H-1-NMR, C-13-NMR and FAB(+)-MS spectral data and elemental analyses results. Biological assays revealed that at 0.1 mu M concentration, the most active compounds against AChE were 5n, 5o and 5p that indicated 96.44, 99.83 and 89.70% inhibition rates, respectively. Besides, IC50 value of the compound 5o was determined as 0.011 mu M, whereas IC50 value of standard drug donepezil was 0.054 mu M. The synthesized compounds did not show any notable inhibitory activity against BChE.