Azasugars derived from L-alanine and L-serine were screened for inhibitory activity against ${alpha}$-rhamnosidase. The enantiomers of 1,6-dideoxynojirimycin ($ent$-1,6-dDNJ) (1) and ($2S$,$3R$)-2-(hydroxymethyl)piperidin-3-ol (5) showed highly specific and potent inhibition against ${alpha}$-rhamnosidase with $K_i$ values of 4.2 and $16.6{mu}M$, respectively. Structure of the best inhibitor features the same stereochemical configuration as L-rhamnose at C2, C3, and C4 centers. In kinetic studies, both compounds exhibited competitive inhibition behavior. Compound 1 manifested simple reversible slow-binding inhibition with the following kinetic parameters: ${kappa}_3=1.17nM^{-1};min^{-1}$, ${kappa}_4=5.96{ imes}10^{-3}min^{-1}$, and $K_i^{app}$=5.1 mM.