Pharmaceutical, cosmetic compositions and/or medical devices (I) based on hyaluronic acid, comprise hyaluronic acid or its salts, added with a polyoxyethylene-polyoxypropylene block copolymer i.e. Poloxamer 407 (RTM: Hydrophilic non-ionic surfactant) in an aqueous solvent suitable for an intra-articular or subdermic injection. ACTIVITY : Dermatological. MECHANISM OF ACTION : None given.