The aim of the study was to investigate the effect of exogenous glial cell line derived neurotrophic factor (GDNF) on spinal cord neurons after sciatic nerve axotomy. Upon silicone tubulization of transected sciatic nerve in the adult rat, either 0.9% saline or GDNF solution was injected into the silicone chamber. It was observed by Nissl and enzyme histochemistry staining that exogenous GDNF decreased lesion induced motor neuron death in lateral nucleus of spinal anterior horn and the changes in activity of cholinesterase and acid phosphatase in spinal cord and sensory ganglions. These results suggest that exogenous GDNF is capable of protecting motor neurons from death induced by peripheral nerve injury.