The synthesis of some potent inhibitors of two retaining beta-glycosidases was achieved by introducing aglycon-mimics into the imidazole moiety Of L-arabino azasugar 1. The strongest inhibition was observed with the phenyl-ethyl substituent at C(2) of 1 against beta-D-galactosidase and beta-D-glucosidase, whereas the hydroxymethyl group at C(2) increased only slightly the inhibitory properties. (C) 2003 Published by Elsevier Science Ltd.