Sequestration of disc herniation is important cause of failure of chemonucleolysis. It is important to recongnize this particular variety of disc herniation before considering enzymatic discetomy. Disc herniation were classified into three-anatomical categories. type I: Subligamentous Herniation type II: Extra-ligamentous Herniation type III: Free-extraligamentous Herniation, Sequestratid disc. one-hundred and eight-six cases of herniatid intervertebral disc were evaluated in Department of Orthopedic Surgery, Wonju College of Medicine, Yonsei University and in Department of Orthopedic Surgery, Inchon Christian Hospital from March 1982 to March 1988. The results of study are as follows; l. Among 186 patients, type III sequestrated disc patients were 32 cases(17.2%). 2. The ratio between male and female was about 2:l. 3. The duration of symptoms in type II,III were longer than type I. 4. On examination, the physical changes were more common in type III than in other types. Positive well leg rasing test was prominant finding especially in type III. 5. The myelographic findings, in type III, were irregularity of dural sac at the level of vertebra body both on obligue and lateral view. 6. The C-T findings, in type III, were irregular protruded disc, or caudal or cephalsd migrated disc materials.