Molecular imprint membranes of theophylline (THO) were prepared by the phase inversion technique with acrylonitrile-acrylic acid copolymer. The copolymer cast solution of dimethyl sulfoxide (DMSO) with the THO template was used and coagulated in poor solvent, water. After removal of the template from the solidified copolymer membrane, THO in aqueous solution was permeated as a solute through the resultant membrane by means of pressure driven filtration. It was shown that the uptake of the solute molecule strongly depends on the template concentration in the DMSO cast solution. The increase of the THO concentration in the cast solution caused an increase in the solute taken into the copolymer membrane. Further, the selectivity of the THO-imprinted copolymer membrane was examined by the uptake experiment of caffeine (CAF) solute and was compared with that of THO solute. The total amounts of CAF taken into the membrane are much lower than that of THO substrate. This result supported the conclusion that the membrane records the shape of THO molecule during the phase inversion process. Evidence of the interaction between THO and copolymer was also shown by characterization of the THO-imprinted membrane.