The birth of myelography was presaged by Dandy’s classic description of pneumoencephalography in 1919. After then, many contrast media, such as Pantopaque, Lipiodol, Abrodil, Dimer-X, and Conray-60, were developed and myelography was achieved in widespread popularity for diagnosis in low back pain, especially on the syndrome of herniated intervertebral disc. During the past few years, the picture has changed dramatically because of the availability of Metrizamide, a new, less toxic, non-ionic, aqueous medium. So, the authors have seen and studied 165 cases of. low back pain with respect to the diagnostic classification and clinical acceptance of Metrizamide myelographic examination from May, 1982 to April, 1985 at Department of Orthopaedic Surgery, College of Medicine, Soon Chun Hyang University. The results were summerized as followings; l. Among the 165 cases, myelographic finding was classified in 4 groups and 7 types, and showed as group 1(41), group 2 and type a(46), group 2 and type b(21), group 3 and type a(9), group 3 and type 1(15), group 3 and type c(16), and group 4(17). 2. The predominent type in the 57 operative cases was group 4(46, 27.9%). 3. In clinical analysis, tenderness was predominent in most types, but sensory changes in group 4. 4. Step by step in types, anatomical changes was seen more often than funtional changes in plain X-ray. 5. Myelographic accuracy was coincided with operative findings in 75.4% and 7 cases of false negative and 5 cases of false positive. 6. In disc findings, the extruded type was seen predominently in group 4 as 29.4%. 7. Above group 3 and type a, the prognosis of operative treatment was excellent than conservative.