Cauda equina syndrome has been described as a complex of low back psin, bilateral sciatica, saddle anesthessia and motor weakness in the lower extremity that progress to paraplegia with bladder and bowel incontinence. The syndrome is uncommon, accouting spproximately 1–16% of reported cases of lumbar disc herniation, but needs urgent diagnosis and surgical treatment. Clinical observations were carried out on 8 cases of cauda equina syndrome in the Department of Orthopaedic Surgery, Yonsei University College of Medicine from June 1980 through June 1986 and the following results were obtained. 1. The highest incidence, 5 cases(63%), occured in 40 49 year old age group and the sex distribution was 5 males and 3 females. 2. Eight cases fell into two clinical groups. group 1(3 cases) presented with a sudden onset without any previous history of low back pain and group 2(5 cases) presented with a incidious onset with history of recurrent low back pain. 3. Preoperative myelogram revealed a totsl block to the flow of the contrsst medium in all cases. 4. Wide laminectomy and discectomy were performed in all cases within 2 weeks after the onset of bladder symptom and 3 cases with two levels of disc prolapse were found. 5. Among total 11 levels of disc prolapse, there was 5 levels of L5-S1, 4 levels of L4-5 and 2 levels of L3-4. 6. The duration of the preoperative bladder symptom was 3.3 days in group 1 and 6.4 days in group 2. 7. With a minimum of 6 months follow up, motor power wss fully recovered in 5 cases, sensory in 6 cases and bladder function in 4 cases.