Epoxide hydrolases are ubiquitous enzymes able to hydrolyse an epoxide to its corresponding vicinal diol. These hydrolases have been shown often to be highly enantio-and regioselective, thus allowing both the epoxide and the diol to be prepared at high enantiomeric purity. Because these products show high chemical versatility, they are important for the synthesis of various biologically active products. Recent studies have provided valuable information on the molecular structure of these enzymes, as well as insight to the enzymatic mechanisms involved.