Ganglion cell axons regrew to approximately their normal length (2 cm) when autologous peripheral nerve segments were inserted into the retina of adult rats for 4-18 weeks. Retrograde labeling from the graft with HRP or combinations of two different fluorescent dyes applied to the optic tract and graft demonstrate that axons growing into the nerve transplants originated from axotomized ganglion cells rather than by sprouting of undamaged neurons. Axonal injury and graft proximity to neuronal somata appear as requisites for the elongation of these fibers.