The interactions of cyclodextrins (CDs) with poly(N-acryloyl-amino acids) (pAXaa) were investigated by H-1 NMR and two dimensional nuclear Overhauser effect spectroscopy (2D NOESY) to elucidate the effect of attachment of amino acid residues to the polymer chain. Using the H-1 NMR data measured at varying pAXaa concentrations, apparent association constants (K) were roughly estimated for the CDs/pAXaa systems. These apparent K values indicated that alpha-CD interacted with poly(N-acryloylphenylalanine) and with poly(N-acryloyltyrosine) and beta-CD and gamma-CD interacted with poly(N-acryloyltryptophan). Comparison of these apparent K values with those for the model compounds, i.e., amino acid sodium salts, revealed that the effect of attachment of amino acid residues to the polymer chain was stronger for a smaller amino acid residue. (C) 2010 Elsevier Ltd. All rights reserved.