The neuronal phosphoprotein GAP-43 has been implicated in neuritogenesis during developmental stages of the nervous system and in regenerative processes and neuronal plasticity in the adult. It was previously reported that the level of increased GAP-43 expression in facial motor neurons following crush injury or nerve resection was paralleled the process of axonal regeneration. Since the optimal timing of repair after facial nerve transection injury has been debated for several decades, the author designed this study for the evaluation of optimal timing of facial nerve repair after injury by using the level of GAP-43 expression in facial motor neurons as a marker of neural regeneration. The increased expression of GAP-43 in facial motor neurons was returned to undetectable level by 4 weeks following the compression injury and by 8 weeks following the nerve transection and immediate end-to-end anastomosis, while it was maintained for at least 16 weeks after the nerve ligation and 1 week delayed anastomosis. This study suggests that the best functional outcomes could be obtained when the transected facial nerve is repaired as early as possible.