Study Design: A prospective study Objectives: To analyze the serial results of selective nerve root blocks in herniated lumbar disc patients. Literature Review Summary: To our knowledge there has been no study demonstrating the serial efficacy of root blocks for patients with a herniated lumbar disc only. Materials and Methods: Selective nerve root blocks were performed in 36 patients who had a lumbar disc herniation only, with radiculopathy, between November 2002 and April 2003. The diagnoses were made by CT or MRI, which agreed with the symptoms and physical examinations. There were 31 men and 5 women, with a mean age of 28.2 years. The mean interval between the onset and procedure was 7.6 weeks, ranging from 1 to 26 weeks. Monoand double-segment injections were used in 18 cases, respectwely. The straight leg raising angle, visual analogue pain scale, and motor and sensory functions were investigated before, immediately, 2 days, and 1 and 3 months after the procedure. Results: The mean straight leg raising angle improved significantly, from 28±9°to 53±18°, immediately, and was maintained until 3 months after the procedure (P<0.001). The visual analogue pain scale was also improved, from 4.6±0.9 to 2.0±1 . 5 , immediately, and was maintained until 3 months after the procedure (P<0.001). Two of ten patients with motor weakness, and six of eighteen with sensory deficit were improved. There was no procedure related complication; however, surgical treatment was performed in two patients who showed no improvement until 3 months. Conclusions: Selective nerve root block is a safe and effective treatment method to obtain a rapid and remarkable improvement of radiculopathy in herniated lumbar disc patients.