We have developed a new method for HPLC which uses packing materials modified with a temperature-responsive polymer, poly(N-isopropylacrylamide). The surface properties and functions of the stationary phases are controlled by the external temperature. In the proposed chromatographic system, the elution of target substances is controlled by only a small change in the column temperatures. (C) 1998 Elsevier Science B.V. All rights reserved.