The soluble epoxide hydrolase (sEH) is a key enzyme in the metabolism of epoxy-fatty acids, signaling molecules involved in numerous biologies. Toward finding novel inhibitors of sEH, a library of known drugs was tested for inhibition of sEH. We found that fulvestrant, an anticancer agent, is a potent (KI=26 nM) competitive inhibitor of sEH. From this observation, we found that alkyl-sulfoxides represent a new kind of pharmacophore for the inhibition of sEH.