Polyurethanes are widely used for biomedical applications, but there is still a constant search for improved blood-compatible materials. We studied a material (PUPA) obtained by the interconnection between a poly(amido-amine), N2LL, capable of forming stable complexes with heparin and a commercial polyurethane, Pellethane 2363-80AE, using hexamethylenediisocyanate as the crosslinking agent. The amount of absorbed heparin (evaluated by biological tests) was generally much higher than that found on the poly(amido-amine) surface-grafted polyurethane.