Results on trehalose/water solutions by neutron diffraction are reported. The analysis of the partial structure factors obtained by neutron diffraction on trehalose/water solutions is interpreted in terms of a destructuring effect of trehalose on the tetrahedral H-bond network of water. This hypothesis, suggested by a previous analysis of the Raman intramolecular OH stretching band, can account for the greater cryoprotective action of trehalose on biological structures. (C) 2002 Elsevier Science B.V. All rights reserved.