OBJECTIVE Polybutester suture is more easily stretched than other vascular sutures and may produce more compliant anastomoses. The effects of using polybutester and polypropylene sutures were compared acutely in arterial autografts and in chronic implants of cephalic vein grafts into the femoral arteries of dogs. METHODS Paraanastomotic profiles of diameter and compliance were measured with echo-tracked ultrasonography, and profiles of intimal thickening were generated from histologic sections of the vessels harvested after 3 months. RESULTS Polybutester produced more compliant anastomoses, compared with polypropylene, in arterial autografts (in vitro: 5.9% +/- 2.0% vs 3.3% +/- 0.6% diameter change/100 mm Hg, p < 0.01; in vivo: 3.1% +/- 1.1% vs 1.6% +/- 0.5%, p < 0.05), but this difference was not observed with vein as the graft material, either initially (1.1% +/- 1.2% vs 1.7% +/- 0.5%) or after 3 months (2.1% +/- 1.2% vs 2.4% +/- 0.8%). This dichotomy may reflect a governing influence of the stiffer veingrafts, compared with host artery (2.6% +/- 1.0% vs 5.4% +/- 1.2%), or the use of suboptimal tension on the polybutester suture when creating the anastomosis. CONCLUSIONS Both sutures produced similar compliance and thickness profiles. Polybutester initially produces a more compliant anastomosis when both artery and graft are compliant, reducing anastomotic compliance mismatch. However, this benefit may not apply when the anastomosis includes a vessel of low compliance.