Abstract To evaluate the potential of a supporting, compliant, biodegradable prosthesis to function as a temporary protective scaffold for autologous vein grafts in the arterial circulation, we implanted vein grafts into the carotid arteries of rabbits, either with (composite grafts) or without (control grafts) such a supporting prosthesis, and evaluated them up to 6 weeks. The control vein grafts showed edema and severe medial disruption with infiltration of polymorphonuclear cells on day 1. Over the study, irregular fibrocyte formation resulted in the formation of a fibrotic vein wall. In contrast, the composite vein grafts showed preservation of smooth muscle cell layers and elastic laminae with a minor inflammatory response. Regular proliferation of fibroblasts, which in some areas were circularly oriented, was observed. We conclude that a supporting, compliant, biodegradable prosthesis can function as a protective scaffold for vein grafts in the arterial circulation, thus reducing damage to the vein graft wall and allowing gradual arterialization.