Hyaluronic Acid (HA) is a biopolymer naturally occurring in many biological systems, including the human body with vital roles in the eye, skin and joints due to its unique viscoelastic properties.The rheological behaviour of HA solutions is directly linked to the macromolecular structure but also to intermolecular interactions (when outside the dilute regime). It is therefore relevant to couple rheological measurements ((already and sistematically carried out by the applicants) with structural studies in a physiological environment and at molecular weights and concentrations similar to those found in the various tissues and biomedical products. In addition HA is an ideal system to study semi-rigid polyelectrolytes, theoretical prediction can therefore be tested and compared to a real system.