A highly enantioselective preparation (92-99% enantiomeric excess, 100% conversion) of various 4-aryl-2-hydroxy but-3-enoic carboxylic acid esters from the corresponding 4-phenyl-2-keto but-3-enoic acid esters mediated by plant cell cultures of Daucus carota under mild and environmentally benign conditions in aqueous medium is described. © 2003 Elsevier B.V. All rights reserved.