C 2 -Symmetrical tetrahydroxyazepanes were synthesized as inhibitors for glycosidases. Tetrahydroxyazepane 1 is a non-specific inhibitor of various glycosidases, while compounds 2, 3 and 4 specifically inhibit β-N-acetylglucosaminidase, β-glucosidase, and a-fucosidase, respectively, with K i in the micromolar range. Compound 1 is not an inhibitor of HIV/FIV proteases, but its 3,6-difluorobenzyl derivatives are moderate inhibitors of both enzymes.