The present invention relates to the synthesis of a haemocompatible polymer, consisting of a polyurethane bound covalently to sulphated hyaluronic acid. These sulfated derivatives have anticoagulative, non-thrombogenic, antiviral and anti-inflammatory properties. They also have the ability to inhibit platelet adhesion, aggregation and activation. The invention is particularly advantageous in resisting the enzyme hyaluronidase, therefore ensuring anti-coagulant activities for longer periods of time when compared to similar compounds. This biocompatible polymer material is well suited for surgical or other medicinal uses.