The present invention relates to an improved process for the production of sulfated hyaluronic acid (HA), sulfated HA-derivatives and/or mixtures thereof, having a high purity and a sulfation degree ranging from 1 to 3, which comprises the following steps: a) solubilization of HA-Na or HA-derivative-Na, in an aprotic solvent in the presence of an organic sulfonic acid； b) sulfation of the solution obtained by the addition of an excess of sulfating agents； c) precipitation in ethanol until a precipitate is obtained； d) solubilization of the precipitate thus obtained in a mixture of water and the aprotic solvent used in step a), in the presence of an excess of NaCl, with a pH adjustment within a range of 3 to 4； e) further precipitation with ethanol until a powder is obtained； f) washings of the powder coming from step e) and drying the product thus obtained under vacuum. The present invention also relates to sulfated HA, sulfated HA derivatives and/or mixtures thereof, having a high purity and sulfation degree ranging from 1 to 3, thus prepared, and the relative pharmaceutical mixtures.
