A. Michel Peyrard* and Yannick Sire**

*Laboratoire de Physique, Ecole Normale SupŽerieure de Lyon 46 allŽee d Italie, 69364 Lyon Cedex 07, France

** Laboratoire MathŽematiques pour l Industrie et la Physique, INSA, dŽep. GMM, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France


This report, initially prepared to introduce a discussion on breathers in biomolecules, discusses some experimental results and their connection with theory. Classical vibrations are considered first and quantum effects are discussed in a second part. The paper does not intend to be a complete review of nonlinear localisation in molecules, but instead it introduces and discusses a few examples with the aim of stimulating thoughts and hopefully further experimental studies or theoretical investigations paying particular attention to the experimental aspects.