1. An enterogenous cyst lying in the cauda equina opposite the third lumbar vertebra, and associated with spina bifida occulta of the fifth lumbar vertebra and spondylolisthesis of the fifth lumbar on the first sacral vertebra, is described in a man aged thirty-five suffering from chronic low back pain and sciatica.

2. Current embryological theories concerning the formation of intraspinal enterogenous cysts from primitive gut cells are further substantiated by the features of this case.