Lipase from Rhizopus sp. was immobilized in the polymer matrix prepared by polymerization of n -viny1-2-pyrrolidone, 2-hydroxymethacrylate or n-isopropylacrylamide. The esterification of oleic acid and glycerol was carried out at 310 K by using the immobilized lipase or free lipase. The selectivity of monoolein was dependent on the hydrohobicity of the polymer matrix immobilizing lipase. The hydrophilic polymer provided a high selectivity for monoolein in the esterification. It was found that controlling the hydrophobicity of the enzyme-immobilized matrix allowed the final constitution of the equilibrium state to be shifted.