One hundred and fifty-four operative cases of herniated intervertebral disc were evaluated in department of Orthopedic Surgery, National Police Hospital from June 1973 to May 1979. The results were obtained as follows: 1. Out of the 154 patients, there were 137 male and 17 female cases. The ratio between male and female was 8:1. 2. The majority (72%) of the herniated intervertebral disc was found in the age group of 20 to 40 years. 3. The most common site of the lesion was between L4 and L5 vertebrae (70%). 4. About 90% of the patient showed significant sign in myelographic and clinical studies. 5. To prevent adhesion of sciatic nerve & dura after the operation, spraying the methyl-prednisolone over the operative site and covering dura with fat in spinal canal could be resulted in good method. 6. The dissecting type is considered to be what operators should observe attentively during the operation. 7. The result of treatment was excellent in 94 cases (61%) and good in 47 cases (30%).