In this study, we evaluated the role of the Netrin-1 receptor UNC5b (Uncoordinated), a neuronal guidance molecule, during peripheral nerve regeneration using the mouse median nerve model. Materials and methods: Using Western blot analysis, we examined the expression changes of UNC5b after transection and microsurgical repair of the mouse median nerve distal to the transection site. We evaluated the histomorphometrical changes and functional recovery of the grasping force after median nerve transection and repair in wild-type (WT) mice and UNC5b+/− heterozygous mice. Results: In Western blot analysis, we could show a high increase of UNC5b in the nerve segment distal to the injury site at day 14. Histomorphometrical analysis did not show any significant differences between WT animals and heterozygous animals. Using the functional grasping test, we could demonstrate that peripheral nerve regeneration is significantly diminished in heterozygous UNC5b+/− mice. Conclusion: By using the mouse median nerve model in transgenic animals, we demonstrate that the Netrin-1 receptor UNC5b plays an important role during peripheral nerve regeneration. © 2012 Wiley Periodicals, Inc. Microsurgery, 2013.