We reviewed 35 patients who received an operation for the Spondylolisthesis from July 1980 to July 1985. The follow-up period between operation and evaluation was at least 14 months and average 32 months. we obtained the following results. 1. The age distribution was from 23 years of age to 70 years of age and the prevalent decade was at the 5th. 2. Sex difference showed male 9 cases and female 26 cases, that is, female preponderance about 3 times. 3. 24 cases were isthmic type and 11 cases were degenerative type. The ratio between isthmic type and degenerative type was about 2: l. 4. Isthmic type was found at the 4th and 5th decades frequently and degenerative type was at 5th and 6th decade frequently. 5. The displacement between L4 and L5 was 21 cases and the displacement between L5 and sacrum was 14 cases. 6. In isthmic type, the displacement between L4 and L5 was 11 cases and the displacement between L5 and sacrum was 13 cases. In degenerative type, the displacement between L4 and L5 was 10 cases and the displacement between L5 and sacrum was 1 case. So the isthmic defect occurred at 2 levels almost equally and degonerative type occurred at L4-5 predominantly. 7. Overall results are excellent 2 cases(6%), good 29 cases(82%), fair 2 cases(6%), and poor 2 cases (6%).