Failures in laminectomy may be due to improper patient selection, of which the largest factor appears to be a lack of recognition of an underlying psychological disorder. Rarely an operative procedure is performed on the wrong side or at the wrong level. A number of elements relating to what might be termed the "wrong operation" fall under the heading of failure to recognize disease, and the largest factor here in our experience has been the inability to explore the wound because of uncontrolled bleeding. The problem also relates to a lack of understanding of the anatomy and potential disorder of the vertebral axis. This then merges with the other factor, failure to deal with disease, which may be unrecognized or, if identified, misinterpreted. Last are those elements for which there is professional responsibility, the most serious being dural or nerve root irritation predisposing to traumatic arachnoiditis.