The neurotrophic activity of fetal brain grafts next to the proximal stump of the transected optic nerve of adult rats was investigated. Axotomy (n = 25) reduced the original retinal ganglion cell population by 90% and the mean neuron size by one-third within 30 days. No increase in number or size of the surviving neurons could be found in any group receiving an embryonic brain graft (E16; spinal cord: n = 16, cerebral cortex: n = 16, tectum: n = 15, thalamus: n = 17) at the site of optic nerve transection, despite good survival of transplants. Although no positive effect on axotomized retinal ganglion cells could be found after transplantation of embryonic central nervous system structures, the same experimental model of the optic nerve seems to be valuable for further investigations of degeneration of traumatized retinal ganglion cells.