The effects of a new neurotrophic pyrimidine derivative of MS-430 on nerve regeneration was examined using Wistar rats whose left sciatic nerve had been subjected to controlled injury. 2. The functional recovery and the packing density of common peroneal nerve axons were significantly enhanced with the administration of 3 mg/kg/day of MS-430. 3. These results suggest that MS-430 is a promising candidate as a neurotrophic drug for clinical use.