The synthesis of new materials (PUPAs) based on a commercial polyurethane and a heparin-complexing polymer, poly(amido-amine), was studied. PUPAs are capable of adsorbing heparin because the basic nitrogens of poly(amido-amine), once protonated, interact with the negative charges carried by the heparin molecule. Six different samples of PUPA were synthesized having a varied ratio of the components. The quantity of basic nitrogen on the surface and the bound heparin for each sample was determined. Two different kinds of heparin are present on a PUPA surface: one is strongly bound but can be detached by 0.1 M NaOH solution, the other is physically adsorbed and is slowly released by a stream of saline solution. A relationship between the quantity of strongly bound heparin and basic nitrogen was found. SEM and FTIR-ATR analysis were performed on all the PUPA samples. The mechanical characteristics change according to chemical composition.