Spondylolisthesis, frequently encountered problems with increasing incidence, has been recognizid as an important clinical entity in orthopaedic field. Several methods were applicated as operative treatment of spondylolisthesis; posterior fusion or H-graft, posterolateral fusion, anterior fusion, fixation with internal devices and etc. During the past 12 years from March 1972 to February 1984, 34 patients among the 42 patients were treated surgically at Department of Orthopaedic Surgery of Ewha Womans University Hospital and following results were obtained. 1. The average age was 45.2 years(19 ~ 64 years) and female was predominent(64.7%). Isthmic type was 17 patients(50.0%), degenerative type was 13 patients(38.2%) and dysplastic type was 4 patients(11.8%). Below 40 year old, dysplastic and isthmic type were predominent and degenerative type was more common in the age group above forties. 2. The most prevalent site was L5-Sl; 21 cases(61.8%) and L4-5; 13 cases(38.2%) in orders. In isthmic type L5-Sl was 13 cases and in degenerative type, L4-L5 was 9 cases. By Meyerding classification, grade I was most common(26 patients, 76.5%). 3. The clinical pictures were low back pain only and little improvement with conservative treatment(type I: 9 patients), low back pain with sciatica(type II: 13), type II plus neurologic signs such as motor weakness, sensory change or change of D.T.R(type III, 10) and little low back pain with mainly sciatica(type IV, 2). 4. Of 34 patients, anterior interbody fusion were done in 10 patients ; posterior and posterolateral fusion with decompression were done in 22 patients. Only laminectomy were done in 2 patients(type IV). 5. Fusion rate was observed in 21 patients(95.5%) among 22 patients with posterior or posterolateral fusion and 8(80%) among the 10 patients with anterior fusion. Postopertive functional results by Gill's criteria were excellent or good in 31 patients(91%). 6. There were no difference in fusion rate and functional results in operative methods.