Retrospective review of a large series of patients who underwent spinal surgery at a single institution during a 10-year period. To further clarify the frequency of incidental durotomy during spine surgery, its treatment, associated complications, and results of long-term clinical follow-up. Incidental durotomy is a relatively common occurrence during spinal surgery. There remains significant concern about it despite reports of good associated clinical outcomes. There have been few large clinical series on the subject. A retrospective review was conducted of clinical and surgical records and radiographic data for consecutive patients who underwent spinal surgery performed by the two senior surgeons from January 1989 through December 1998. A total of 2144 patients were reviewed, and 74 were found to have dural tears occurring during or before surgery. Incidental durotomy occurred at the time of surgery in 66 patients (3.1% overall incidence). Incidence varied according to the specific procedure performed but was highest in the group that underwent revision surgery. The incidence of clinically significant durotomies occurring during surgery but not identified at the time was 0.28%. All dural tears that occurred during surgery and were recognized (60 of 66) were repaired primarily. Pseudomeningoceles developed in five of the remaining six patients. All six patients had subsequent surgical repair of dural defects because of failure of conservative therapy. A mean follow-up of 22.4 months was available and showed good long-term clinical results for all patients. Incidental durotomy, if recognized and treated appropriately, does not lead to long-term sequelae.