The nerve root block or selective nerve root block is one of the primarily preoperative diagnostic tool to identify and confirm the lesion site of primary cause of pain and that is considered as one component of a comprehensive treatment program. The purpose of our study is to evaluate the effect and duration of the pain control by selective spinal nerve root block as a conservative treatment in patients presenting with chronic or recurrent sciatica. The authors performed 95 selective nerve root blocks in 72 patients from Sep. 1994 to May. 1996, (mean follow up 11.6 month) at the department of orthopedic surgery, Kosin University Gospel Hospital, and the results were as follows: 1. Among 72 cases, spinal stenosis was in 45 cases (62.5%), HIVD in 19 cases (26.4%), failed back syndrome in 5 cases (6.9%), spondylosis in 2 cases (2.8%), and spondylolisthesis in I case (1.4%). 2. In 72 cases, improved more than 50% of sciatica were 61 cases (84.7%) at 3 hours, 53 cases (73.6%) at I week, 35 cases (48.6%) at 1 month, 33 cases (45.8%) at 3 months, and 33 cases (45.8%) at 6 months respectively. 3. At last follow-up, excellent and good results were 35 cases (48.6%), fair results were 25 cases (34.7%) and poor results were 12 cases (16.7%) by the Kirkaldy-Willis criteria. 4. Complications were 1 case of transient hypotension, 2 cases of severe paresthesia, but subsided without residual complication. Therefore, the selective nerve root block is one of the valuable procedure that is helpful and extremely safe in useful treatment for radicular pain associated with lumbar disease. And the trial of selective nerve root block was recommended before deciding surgical intervention on an outpatient basis.