A crosslinked, L-histidyl group-introduced polymer catalyst, which was imprinted by a transition-state analogue of phenyl 1-benzyloxycarbonylamino-3-methylpentylphosphonate in the hydrolysis of p-nitrophenyl N-carbobenzoxy-L-leucinate, was prepared from poly(2-methyl-2-oxazoline). The catalyst enhanced the hydrolysis of the L-leucine ester, in comparison to the hydrolysis of the L-phenylalanine and L-alanine esters.