OBJECTIVE: We investigated whether axonal transport of a kind of neuron-specific toxin (OX7-saporin) led to selective loss of neurons in DRG and ventral horn of spinal cord. MATERIALS AND METHODS: Thirty adults Sprague-Dewley rats weighting 200-250 g at the beginning were randomly divided into three groups. Group A (GA, n=10): the left common peroneal nerve and posterior tibial nerve were severed to allow neuroma formation. Group B (GB, n=10): the nerves were cut as GA and then 2 (l of OX7-saporin was injected into the posterior tibial nerve. While in Group C (GC, n=10), 2 (l of Dulbecco's PBS was injected into the posterior tibial nerve. After three and six weeks, the rats were sacrificed by transcadially perfusion. The common peroneal nerve, tibial nerve, sciatic nerve dorsal and ventral roots were harvested and routinely processed for light and electronic evaluations. RESULTS: There was typical neuromas formation by gross observation in GA. The same findings were found in GC. However, there was a tapered tip instead of neuromatous bulb in GB. Microscopically, the neuroma was composed of entangled mass of nerve fibers with a large amount of regenerating axons. In marked contrast, there was extensive degenerating change of nerve fibers in OX7-saporin treated rats. The degeneration was in a well-defined portion of sciatic nerve corresponding to the fascicles that form the posterior tibial nerve. The degeneration was also found in dorsal and ventral roots in GB. CONCLUSION: The present study demonstrated that intraneural injection of OX7-saporin could effectively prevent neuroma formation by wiping out and/or inhibiting the regeneration of injuried nerve fibers in the rats. This kind of neuron-specific neurotoxin could be as a potential molecular neurosurgical approach for prevention neuroma formation in the future. This study convinced that intaneural injection OX7-saporin could effectively prevent neuroma formation