This is an interesting group of patients who have in common the roentgenographic finding of degenerative spondylolisthesis. This is a retrospective, uncontrolled review. It would be interesting to have a similar matched group of 132 patients in the same age group without degenerative spondylolisthesis but with marked degenerative changes to compare symptoms, signs, and outcome of treatment. We have not had adequate follow-up on the nonoperative patients and therefore cannot provide data for comparison with the operative group. A total of 51 of our 132 patients had 83 operative procedures. Twenty-five percent, or 13 patients, showed a degenerative spondylolisthesis at L4-5 with a previous history of having undergone a disk excision at the same level. Seven of the 51 patients (14%) developed a progressive slip following surgery. None of these patients had previous fusion. Two patients of the 17 that we operated on primarily (12%) subsequently developed a progressive symptomatic slip. We have concluded from this review that spinal fusion should be performed in conjunction with decompression more frequently in patients with degenerative spondylolisthesis despite the fact that the majority of these patients are over 60 years of age.