Abstract: Objective To introduce a modified catheterization of the lumbar spinal subarachnoid space in mice. Methods Fifty male C57BL/6J mice were randomly divided into two groups: Wu-method group (n=30) and modified-method group (n=20). The PE-10 catheter was implanted into lumbar spinal subarachnoid space with two different surgical proceduces. The results of catheterization and spinal nectrotom were compared. 10 days post surgery, the qualified mice were used for tesing locomotor function and analgesic effect of morphine following intratheal injection (i.t.). Result There were no significant differences between two groups in intraoperative death rate, motor dysfunction, spinal cord damage or hemorrhage, lidocaine test and methylen blue lication (P＞0.10), ten days post surgery, there were no significant differences in locomotor function or the analgesic effect of morphine i.t.(P＞0.10).Compared with the Wu-method group, a marked lower rate of catheter leakage，catheterization failure and catheter withdrawal or off was observed in Modified-method group (P＜0.05). Conclusions This modified method is simple and reliable with a high success rate，should be suitable for catheterization of the lumbar spinal subarachnoid space in mice.

Key words: Intrathecal, Mice, PE-10