The first synthesis of the novel azasugar α-L-homofuconojirimycin is reported. The biological activity of this compound is described and is shown to be more specific for α-L-fucosidase than compounds previously tested. Glycosidase inhibitors based upon azasugars have attracted considerable interest as tools for the study of a number of biochemical pathways and disease states. Several groups have reported synthetic and semisynthetic approaches to azasugar inhibitors of α-L-fucosidases. Fleet et al have reported the synthesis of 6-epi-α-L-homofuconojirimycin 1 and β-L-homofuconojirimycin 2. This paper describes the first synthesis of α-L-homofuconojirimycin 3, a closer aza analogue of L-fucose 4 than 1 or 2. We also report the ability of this compound to act as an inhibitor of glycosidases.