As proteasomeinhibitors, a series of novel macrocyclic dipeptide N-benzyl amides were designed, synthesized and evaluated. Most of them exhibited potent proteasome inhibition and excellent anti-proliferative activity against RPMI 8226, MM1S, and MV-4-11 cell lines. As the most distinguished one among this series, compound 23h displayed potent and selectiveproteasome inhibitory potency (IC50: β5c = 29 nM