Replica-exchange molecular dynamics simulations have been performed on a 10-residue peptide in ethanol as well as in water that were treated explicitly with 32 replicas in the range of 298-600 K. It has been found that the peptide tends to form compact structures in ethanol whereas it is extended in water. The numbers of intramolecular hydrogen bonds and turn structures are both larger in ethanol than in water, and this difference enhances the tendency of forming secondary structures in ethanol. (c) 2005 Elsevier B.V. All rights reserved.