Objectives: This study aims to examine the effect of surgical timing on the sphincter function and improvement of motor function in patientswith cauda equine syndrome (CES) due to lumbar disc herniation (LDH).Patients and methods: Between January 2005 and December 2013, a total of 33 patients (18 males, 15 females; mean age 48.6±2.2 years, range,24 to 73 years) who underwent lumbar spinal surgery and were diagnosed with CES due to LDH were retrospectively analyzed. Data includingdemographics, muscle weakness, sensory deficit, sphincter control, LDH level, time from the initiation of symptoms to admission, and time tosurgery were documented. The latest muscle weakness, sensory deficits, and sphincter control were also recorded. The patients were divided intotwo groups according to the rate of muscle strength improvement and data including age, sex, and operation time were compared.Results: The weakness remained unchanged in 11 (33.3%), improved in 13 (39.4%), and returned to normal in nine (27.3%) patients. Sphinctercontrol resolved in five patients. Sensory loss resolved in two patients. While admission duration was shorter in the group with improvedmuscle strength (p=0.02), there was no significant difference in the time to surgery (p=0.63). Logistic regression analyses revealed that onlythe admission within 0 to 24 hours was significant for the muscle strength improvement (regression coeeficient [B]=2.83, standard error[SE]=0.86, p=0.006).Conclusion: A significant improvement in the motor strength can be achieved in patients with CES who are operated within 24 hours. Onthe other hand, patients with CES should be received surgery immediately when first seen, regardless of the time, since the muscle strengthis slightly improved.