Polyurethanes (PUs) are considered currently as one of the established bio compatible and blood compatible biomaterials offering tremendous structure-property relationship. But few limitations such as low resistance to micro-emboli and thrombi are still associated with these biomaterials that restricted their applications and hence need to be modified. Heparin, a highly sulfonated and negatively charged member of glycosaminoglycan family is well established for their anti-thrombin, anticoagulant and many biological activities that make it a highly attractive candidate capable of modifying or tailoring polymer properties. Incorporation of heparin for the improvement of biocompatibility of PUs is an interesting approach and enabling emerging technology. This review focuses on the methods used for modification of PUs via heparin with their pros and cons. The major PU-heparin systems with the recent developments and their possible biomedical applications are discussed.