The new chiral salen complexes were synthesized and supported on mesoporous MCM-41 through the condensation of 3-aminopropyltrimethoxysilane and 2,6-diformyl-4-tert-butylphenol by the multi-grafting method. The immobilized optically active Co(II) salen complexes showed a very high enantioselectivity in the asymmetric borohydride reduction of aromatic ketones. The chiral salen Co(II) complexes immobilized over MCM-41 were stable during the reaction and exhibited a relatively high enantioselectivity for the reduction of ketones as compared with the homogeneous salen catalysts.