It is important to follow strict indications for surgery and recognize prognostic factors in order to get good results in the surgical treatment of herniated nucleus pulposus. 55 patients with herniated nucleus pulposus were studied who had had laminectomy and discectomy and were followed up for more than 1 year in order to analyze the correlation between various factors including history, physical examination and radiologic finding and surgical results. Age, sex, symptom duration, location of the herniation, smoking, occupation, physical examination, disc height change, MRI findings, operation time and bleeding volume were evaluated as prognostic factors that seemed to influence surgical result. The results are as follow 1. Female had significantly better surgical results than male (P<0.05). 2. Non-smokers had significantly better surgical result than smokers (P<0.01). 3. In MRI finding, protruded disc had significantly better surgical result when it had involved spinal canal posterolaterally than centrally (P<0.01). 4. The less bleeding volume, the better surgical result (P<0.05).