Abstract The interaction of water-soluble polymer conjugates of the anticancer agent paclitaxel and albumin as model protein has been investigated using fluorescence spectroscopy and NMR. Drugs and drug conjugates can enter the hydrophobic core of albumin; the kinetics of the interaction with the fluorophore, however, differs. Given the information about the steric situation of the formed complexes, some aspects of molecular engineering of the drug are discussed.