The rate of regrowth of ganglion cell axons regenerating into a peripheral nerve graft implanted into the retina of adult hamster was measured, utilizing the method of retrograde labelling by horseradish peroxidase. The fastest regrowing axons were found, after an initial delay of 4.5 days, to extend at about 2 mm/day in the graft. The role of the cell body in controlling the rate of axonal regeneration was briefly discussed.