This mini-review provides a general overview about α-glycosidases and β-glycosidases. The importance of these enzymes is reflected by the number of diseases in humans that result from the lack or dysfunction of one of them. Different types of inhibitors targeting these enzymes are discussed and particular focus is given to those ones that are used in the treatment of viral infections, diabetes, tumor metastasis, and glycosyl sphingolipid (GSL) storage disease among other diseases. Further details are also given about metabolic disorders, such as Pompe and Gaucher diseases, that result from the lack of activity of one of these glycosidases.