63 cases of spondyloisthesis were studies retrospecitively, which were treated surgically at department of orthopedic surgery of InJe University Paik Hospital from June 1979 to 1989, and results were observed as follow;l. Isthmic type is the most common (47 cases, 74% ) in etiology. 2. The 4th Lumbar vertebral involvement is common (37 cases, 59%). 3. Low back pain is the most common complaint (54 cases, 86%). 4. Post-operative fuctional results by Gill's criteria were excellent or good in 52 cases (83%).