Abstract: The invention relates to hyaluronic acid nanoparticles for the administration of at least one active ingredient. The inventive nanoparticles comprise hyaluronic acid in salt form a positively-charged polymer, a polyanionic salt and at least one active ingredient. The method of obtaining the aforementioned nanoparticles comprises the following steps consisting in: preparing an aqueous solution of a hyaluronic acid salt, preparing an aqueous solution of a cationic polymer, adding a polyanionic salt to the solution of the hyaluronic acid salt, and stir-mixing said solutions such as to produce the nanoparticles, the active ingredient being dissolved in one of the initial solutions or in the suspension of nanoparticles obtained in order to be absorbed on the nanoparticles. The invention also relates to pharmaceutical and cosmetic compositions comprising the above-mentioned nanoparticles.