The basis of surgical treatment of spondylolisthesis lies in the restoration of stability to the unstable spine and the decompression of the entrapped nerve root. Knodt's distraction rod has been thought to be one of effective distraction instruments promoting fusion for lumbar spine surgery. From December 1981 to May 1987, we performed surgical treatment of spondylolisthesis with Knodt's distraction rod instrumentation in 15 patients (Group I ) and fusion in situ in 7 patients (Group II ). Clinical analysis and changes of radiographic measurements of above two methods were evaluated and obtained following results. l. In Group I, the percentage slip and slip angle decreased to 12.1 ±6.3% and 0.2 ±6.6°, postoperatively, from 20.9 ±8.4% and 7.5 ±5.6°, respectively. In Group II, changed from 13.4 ±9.4%, 7.8 ±6.1°to 11.4 ±9.6%, 11.0 ±5.2°, respectively. 2. In Group I, the average reduction rate was 42.1% postoperatively, but decreased to 20.5% at follow-up. 3. The percentage posterior disc height increased to 49.0 ±6.7% postoperatively, from 27.4 ±10.0% in Group I and decreased to 34.7 ±5.3% at follow-up. But, in Group II, no significant changes observed. 4. The lumbar lordosis in Group I and Group II, decreased to 26.0 ±8.3°and 29.8 ±13.8°, postoperatively, from 35.5 ±7.8°and 37.6 ±1.4°, respectively. 5. There was no significant difference in clinical results between two groups. 6. Postoperstive complications in Group I, were one case of rod breakage with pseudarthrosis, 3 cases of voiding difficulty and superficial wound infection, in Group II, were 2 cases of superficial wound infection and 3 cases of transient voiding diffeculty.