Eleven N-phenyl- and 11 N-benzothiazolyl-2-(4-(2,3,4-trimethoxybenzyl)piperazin-1-yl)acetamides have been synthesised by a simple and efficient method. The 22 novel compounds were tested for their in vitro biological efficacy against two Gram-positive bacteria, three Gram-negative bacteria, two fungi and Mycobacterium tuberculosis H37Rv. The bioassay results revealed that the majority of the N -benzothiazole-substituted piperazine derivatives exhibited moderate to good bioefficacies with encouraging MICs. The influence of the presence or absence of various electron-withdrawing or -donating functional groups on the aryl acetamide moiety on the different bioassay results is discussed.