When the multiple myelographic defects at lumbosacral region are noted, the prudential effort for decision of appropriate area of surgical decompression would be needed. Fifty four patients who had been treated surgically for the deseases, such as HNP and spinal stenosis, from March in 1982 to Feb. In 1987 at Department of Orthopecdic Surgery, Soonchunhyang University Hospital, were analyzed in order to define the etiology, the level of the defect, indication for the operation and to assess the results of each level which had been operated. The results of the study were as follows. 1. The number of patients, which the multiple indentations were noted in the myelogrsphy, was 54 cases, 29 spinal stenosis, 15 HNP and 10 mixed types. 2. The most common defect levels in myelography were L3-4 snd L4-5, which were 19 cases (35.2%), the next levels were L4-5 and L5S1, which were 16 cases(29.6%), then L3-4, L4-5 and L5S1 were 7 cases(13%) and the other levels were 12 cases(22.2%). 3. The decision for the sppropriste operation area had not be done following to the size of the myelographic defect, but the clinical symptoms and physicsl exsminations. 4. The results were classified ss excellent or good in 79.7%, which was 80% at two levels snd 79.5% at one level. 5. The operation levels could be decressed for the reducing the spinal instability, operation time and possibility of the dangerous conditions and promotion of early restoration and, ambulation, if the severe differences between the results of one and two operation levels were not seen.