Molecular dynamics (MD) has been used to simulate a dilute aqueous solution of a 50-units oligomer model for the thermo-responsive polymer poly(N-isopropylacrylamide) at 300 and 310 K, i.e., below and above its lower critical solution temperature (LCST) in water. Statistical analyses of the system trajectories show that at 310 K the oligomer exhibits a more compact conformation than at 300 K, in qualitative agreement with experiments, and that it is surrounded by a smaller number of first-hydration-shell water molecules. (C) 2004 Elsevier B.V. All rights reserved.