1. These data do not bear out observations by others, that spondylolisthesis is more common in females; about sixty-two per cent. of the patients in this series were men.

2. Trauma appears to be a significant factor in the etiology, although the frequency of congenital defects and the apparent instability of the lumbosacral joint are additional factors. About thirty-eight per cent. of the patients ascribed the cause to trauma.

3. Spondylolisthesis may be partial or complete, with variations of the lumbosacral angle.

4. Symptoms are mainly backache, which comes on either gradually or suddenly; if suddenly, severe trauma is usually associated.

5. The absence of symptoms with the patient at rest, and aggravation of pain on exertion are characteristic.

6. Shortening of the torso, lordosis, and a broadened appearance of the pelvis are common observations.

7. Prominence of the upper posterior border of the sacrum is present to a varying degree.

8. Depression due to displacement of the fifth lumbar vertebra with local tenderness is common.

9. The anteroposterior diameter of the pelvis is lessened, thus narrowing the birth canal.

10. The neurologic signs are usually paresis and modified sensation, limited commonly to the fifth lumbar vertebra and the first sacral segment. Complete paraplegia at this level is impossible unless severe trauma has injured the cord at a higher level. Pain and paraesthesia over the saddle area may be present.

11. Stereoscopic or lateral-view roentgenograms are best, as the anteroposterior-view roentgenograms may not disclose the lesion.

12. Patients are treated by casts, braces, corsets, or fusion of the third, fourth, and fifth lumbar vertebrae and the upper part of the sacrum.