Over the past 11 years, the authors have treated 50 cases of intact arch spondylolisthesis. There were 38 female and 12 male patients, and all but 11 were older than 60 years of age. Almost all had severe low-back pain made worse by standing or walking. Other common manifestations were unilateral leg pain, numbness or weakness of the leg, and evidence of mild cauda equina compression. Severe cauda equina compression was rare. Myelography invariably showed an extradural dorsal compression. A waist deformity was characteristic in many patients, but 12 had a complete block. In 15 patients (30%) the myelographic impression was that of a herniated intervertebral disc. Most subluxations were of L-4 on L-5. At operation, the facets were found to be thickened, distorted, and irregular. All patients were treated with a wide decompression and laminectomy, which included a medial facetectomy of the inferior and superior facets. An intervertebral disc was removed in 10 patients. Follow-up monitoring of 41 patients (for an average period of 36 months) showed that 26 (63%) were pain-free, 11 had less pain, and four were unimproved. Five other patients with short follow-up periods (average 5 months) were all improved.