the disclosure is of articles having reduced thrombogenicity and which are useful for purposes requiring their contact with whole blood . the articles comprise solid , polymeric resin substrates to which there is fixed a compound of the formula : ## str1 ## wherein a represents the residue of sodium heparin after removal of the sodium ion . the articles advantageously exhibit low toxicity and excellent blood compatibility when used for purposes which bring them into contact with whole blood for prolonged periods of time .