The follow-up of these seventy-three cases suggested the following conclusions:

1. The clinical signs alone are not always sufficient to make the diagnosis of herniated nucleus pulposus with sufficient accuracy.

2. When positive, myelography was reliable as a means of localising the hernia.

3. In doubtful cases in which conservative treatment failed a clearly positive myelography turned the scale for a well-indicated operation.

4. In doubtful cases a clearly negative myelography has often rightly been a contra-indication for laminectomy.

5. No serious complication from the use of water-soluble contrast medium for myelography has been encountered.