1. Ten cases of spondylolisthesis with hamstring tightness are reported.
2. The clinical appearance as well as the roentgenographic findings are described, and the associated findings of scoliosis and spina bifida occulta are stressed.
3. Myelograms were available for eight of the ten patients. A complete block was present in five patients and partial obstruction was seen in the remaining three.
4. In seven of the ten patients, the posterior elements of the fifth lumbar vertebra were loose, and a defect in the pars interarticularis was demonstrated at surgery.
5. Satisfactory immediate results were obtained in all patients following laminectomy of the fifth lumbar vertebra and spine fusion (plus sacral osteoplasty in five patients and excision of the disc between the fifth lumbar and first sacral vertebrae in two patients). In one patient there was recurrence of back pain three years after surgery.