The object of the present invention relates to sulfated hyaluronic acid (HAS) for use as regulator agent of the cytokine activity (pro- and anti-inflammatory) and consequently the use of HAS for the preparation of a medicine for the prevention and treatment of pathologies associated with the activation and/or deficiency of cytokines of a pro- and anti-inflammatory nature, including vascular pathologies relating to activation of TNF, IL-1 and IL-6, skin diseases associated with IL-10 deficit, certain viral or immune related diseases, or pathologies associated to the activation of osteoclasts. The Applicant has discovered its capacity in modulating the activity of these particular proteins, and has demonstrated the substantial difference between the different sulfated types known in the state of the art, but above all it has demonstrated an unexpectedly high activity of HAS vs different types and strains of Herpes virus, HIV, Cytomegalovirus and the virus of vesicular stomatitis.
