Aim: To compare the injury effects of 42 °C pulsed radiofrequency (PRF) and 80 °C radiofrequency thermocoagulation (RFTC) lesion on the brachial plexus of rats. Methods: The experiment was carried out at animal laboratory of Beijing Neurosurgical Institute between November 2004 and May 2005. Fifty-five Wistar rats were selected and fifty of the total were randomly divided into PRF group and RFTC group, another five belonged to normal group. PRF was separately applied to the left brachial plexus of rats in the PRF group at 42 °C for 120 s with the pulsed frequency of 2 Hz. The RFTC was used to the same part in the RFTC group at 80 °C for 75 s. The brachial plexus of rats was removed for pathology examination after operation and at 1, 7, 14, 30 days (n=5) after operation. Those in the normal group were not intervened, and the brachial plexus at the same part was got. The minimum stimulus value of voltage and current and the impedance before and after operation were recorded to perform neurofunctional score (0-5 points, 5 points as normal gait). The pathological changes of nerves were observed and the stereology of myelinated nerve was measured. Results: Totally 53 rats were involved in the result analysis. 1 The edema among nerve fibers of PRF group was observed and it was the most serious at 1 day after injury, then gradually palliated at the 7th day. The pathology of RFTC group was characterized by Wallerian degeneration and axon regeneration. 2 The impedance of RFTC group after operation was lower than that of RFTC group before operation and PRF group [(326±65), (392±84), (408±74),P < 0.05]. 3 Compared with the normal group and the PRF group, the average areas, mean diameter and area density of nerve fibers after operation in the RFTC group was higher (P < 0.05), but the quantity of nerve fibers was less (P < 0.05); Compared with the normal group, in the PRF group the quantity after operation and at 1, 7 days and area density at 1, 7 days were lower (P < 0.05). The quantity and area density of nerve fibers at 1st day was the lowest, and the quantity and area density at the 7th day and the quantity of nerve fibers after operation were lower than those at the 14th, 30th days in the PRF group (P < 0.05). 4Compared with before operation and the PRF group, the score after operation in the RFTC group was lower (P < 0.05). Conclusion: PRF is a new treatment method for pain whose lesion is slighter and can recover rapidly, which indicates that its application is safer than the RFTC, and verified that the analgesic effect of PRF does not come true by destroy nerves.