Peripheral nerve injuries are frequent and generate significant deficits. Their treatment sometimes leads to functional recovery but is mostly incomplete or unpredictable, despite the regular use of sophisticated repair techniques. The clinician must clearly understand the peripheral nervous system's responses to injury, which reveal surprising degenerating and spontaneous regenerating abilities. This potential recovery is a peripheral nervous system specificity and follows a relatively complex process. Peripheral neurons depend on glial cell structure and metabolism, inducing a global and dynamic response of the whole axon environment, even in cases of focal lesion, modulated by the initial type and mechanism of injury. Today's progress remains insufficient to improve functional prognosis significantly, but a better understanding of peripheral nerve regenerating processes has opened the door to new medical and surgical advances.