A series of (1H-benzod1,2,3triazol-1-yl)(4-benzylpiperazin-1-yl)methanones and of (1H-benzod1,2,3triazol-1-yl)(4-phenylpiperazin-1-yl)methanones has been prepared and tested on human fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). In the benzylpiperazinyl series, compound 29 (ML30) exhibited an IC50 value of 0.54nM on MAGL, combined with a 1000-fold selectivity versus FAAH, while compounds 11 and 16 acted as potent dual FAAH-MAGL inhibitors (IC50<10nM). In the phenylpiperazinyl series, compounds 37, 38, 42, and 43 displayed IC50 values against MAGL in the nanomolar range, whilst being between one and two orders of magnitude less potent on the FAAH, while compounds 31 and 32 were potent FAAH inhibitors (IC50<20nM) and over 12-fold selective versus MAGL. The key structural determinants driving the structure–activity relationships were explored by the minimization of the inhibitors inside the active site of both enzymes.