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Abstract Background: Fetal Cerebrospinal fluid (CSF) develops viability and proliferation of nerve cells. Also this fluid contains many valuable factors for protection of nervous system injury cells. In this research, the effect of cerebrospinal fluid intraperitoneal injection on alpha motor degeneration after sciatic nerve compression in rat was determined. Materials and Methods: In this experimental-laboratory study, 18 male Wistar rats divided randomly in 3 groups (control, compression, and experimental). In compression and experimental group, right sciatic nerves were highly compressed. CSF was injected in experimental group each three days. After 1 month care, all rats were cordially perused by 10% formaldehyde and their L4-L6 lumbar segments of spinal cord were sampled and with processed for histological examination, the paraffin blocks were serially cut (7mm). Slices were stained with toluidine blue and numerical densities of motoneurons in spinal ventral horn were estimated stereological (dissector) technique. Quantitative data were analyzed by T-test. Results: Significant reduce in motoneurons number of compression group (47026) in comparison with control group (173978) was seen. Also there was significant difference between compression and experimental groups (992±141) in neuron density. Conclusion: CSF intraperitoneal injection may have a beneficial effect in neural regeneration.