Interaction of rat lymphocyte subpopulations (B cells and T cells) with surfaces of poly (N,N-dimethylacrylamide-co-3-acrylamidophenylboronic acid) (DB copolymers) with varying composition was evaluated under a controlled shear stress by using a plane-parallel-type channel equipped with a polymer-coated bottom wall [field-flow fractionation/adhesion chromatography (FFF/AC)]. This method enables to control the hydrodynamic shear stress at the channel wall resulting from the parabolic flow in the channel. The recovery profile of lymphocytes from DB channels was different among each subpopulation, and the selective recovery of T cells from the channel was achieved with most of B cells remaining in the channel. Phenylboronic acid residues in DB copolymers seem to work as binding sites for sugar residues, presumably sialic acid residues, existing on the membrane surface of lymphocytes. Yield and efficiency of the separation are in the practical range for the application in immunological field, allowing this system to be useful as a novel lymphocyte separator.