STUDY DESIGN: Retrospective analysis to evaluate predictive factors of low back pain after discectomy in lumbar disc herniation. OBJECTIVE: We analysed clinical and radiological predictive factors which possibly contribute to postoperative low back pain in herniated lumbar disc disease. SUMMARY OF LITERATURE REVIEW: There was no statistically significant factors which contribute to postoperative low back pain. MATERIALS AND METHODS: Ninety two patients with herniated lumbar disc who were treated by one level simple discectomy from June 1995 to June 2000 were included in this study. They were divided into two groups by severity of postoperative low back pain, back pain group and no back pain group. We analyzed clinical and radiological factors retrospectively in each group by medical records, preoperative radiographs and telephone interview. Then statistical analysis was performed with Chi-square test and logistic regression analysis. Confidence interval was 95%. RESULTS: Eighteen patients (19.6%) were in back pain group and seventy four patients (80.4%) were in no back pain group. Among patients over 50 years old and below 50 years old, the ratio of low back pain after discectomy was 33% and 13.8% respectively (Odds ratio=3.1, confidence interval 1.07~9.03). It was proved statistically that except age factor, such factors as follows did not affect postoperative lower back pain. Sex, smoking, preceeding low back pain before discectomy, level of discectomy, disc space narrowing, bony spur, grade of disc degeneration, presence of high intensity zone of disc. CONCLUSIONS: There was no other significant predictive factors of post-discectomy low back pain than the age over 50 years old.