Well characterized, laboratory-synthesized polymeric materials which have been extensively tested for biocompatibility via initial platelet and protein deposition in an acute ex vivo canine model were placed as interpositional series shunts in canines with chronically implanted iliac arteriovenous shunts ex vivo. Platelet deposition was measured on a base polyurethane block copolymer, a sulfonated ionic derivative, an alkyl grafted (C18) derivative, Biomer, polyethylene, and polydimethylsiloxane for 24 h using radiolabeled platelets. Platelet survival and in vitro aggregation were determined to investigate the effects of the shunting procedure on experimental animals. The viability of adopting a chronic arteriovenous (iliac) shunted canine model for use with series shunts to evaluate polyurethanes having applications as materials in vascular graft construction was investigated and the results compared with acute model data.