Spondylolisthesis has been become of considerable causative disease for low back pain in orthopedic field recently. Twenty-seven patients with spondylolisthesis, who were taken operation during a 7-year period from Jan. 1978 to Dec. 1984 at Department of Orthopedic Surgery of Presbyterian Medical Center, were studied and analized on clinical and radiological aspects and the results of obtained were as follows: 1. The averake age was 41.7 years with a range of 20 to 63 years, and the incidence was more common in female than male in all types. 2. By Wiltse's classification, isthmic type was most common and 19 patients were included and level of spondylolisthesis was common at fourth lumbar vertebra in degenerative type and fifth lumbar vertebra in isthmic type. 3. By Meyerding's grading, 14 patients (52%) were Grade 1, which was most common and the slipping measured by Taillard's method was most common with a range 10% to 19%, which included 13 patients (48%) and average slipping was 21.4%. 4. Meschan's angle was ranged from 5° to 19° with an average of 13.3°. 5. Myelogram was done in 13 patients and 9 of them showed positive findings. 6. Spina bifida was most common developmental abnormal finding and 11 patients (41%) were included. 7. Posterolateral fusion was done in 24 patients and anterior interbody fusion was done in 3 patients. 8. 24 patients who had taken posterolateral fusion were permitted to ambulate early at 2 weeks with Norton-Brown back brace. 9. After over a year follow-up, 23(85%) of 27 patients had satisfactory result. 10. After follow-up, 21(88%) of 24 patients who had taken posterolateral fusion had successful fusion.