In a primate model, nerve regeneration was evaluated across 2- and 5-cm nerve gaps using a synthetic nerve conduit (glycolide trimethylene carbonate, Maxon®) and a biologic conduit (collagen). Two types of conduits from glycolide trimethylene carbonate (Maxon®) were evaluated. The first was fashioned into a tube from a single flat piece of Maxon® mesh. The second was prefabricated in a crimped form. The other material evaluated was a biologic collagen tube. At 14 months, excellent regeneration was noted across the 2-cm nerve gap through both the collagen and Maxon® conduits. At 5 cm, the regeneration, as determined by morphometric analysis, was significantly better across the Maxon® prefabricated, crimped conduit, although regeneration at this longer gap in all experimental groups was significantly less than across the shorter nerve gap. At the longer gap, there was no statistical difference between the groups by electro-physiologic assessment.