STUDY DESIGN: This is a retrospective case control study. OBJECTIVES: To analyze our results following simple discectomy of central massive disc herniation focusing on instability for the usefulness of intervertebral fusion. SUMMARY OF LITERATURE REVIEW: Lumbar instability is a complication of central massive disc herniation. However, there is limited evidence on the correlation between lumbar instability and loss of disc material. MATERIALS AND METHODS: A total of 25 patients who had undergone discectomy for a single-level lumbar disc herniation were followed up for two years. The clinical group (group A) included 12 patients that had a compromised canal with greater than 50% of the herniated disc, while the central axis of the herniated disc was less than 20% deviated from the center axis of the spinal canal, as seen on MRI. The control group (group B) had 13 patients that had a compromised canal with less than 50% of the herniated disc while their axis was more than 20% deviated from the center axis of the spinal canal. Clinical and radiologic instability, pain and functional disability were compared between the two groups. RESULTS: No differences was found between the two groups in clinical instability, radiological instability, visual analogue scale (VAS), and the Oswestry disability index (ODI). CONCLUSIONS: Central massive disc herniation after discectomy did not show a significant difference in clinical or radiological instability from that of other herniation types.