To determine the long-term effects of lower lumbar fusion, 94 subjects were catalogued from medical records. They had a lumbar arthrodesis at the third lumbar level or below and their operations were performed befor 1964. Twenty-four were not located and 8 were decreased. Sixty-two subjects (72% of available sample) completed a telephone interview; 52 subjects completed a comprehensive low back questionnaire; and 33 subjects returned for physical examination, flexion-extension lateral lumbar spine films, and a limited computerized axial tomographic (CAT) scan. In general, the subjects who returned for complete evaluation were representative of the larger sample. Forty of 62 patients were men. Ages ranged from 41 to 83 years; the median age was 66 years, 6 months. Follow-up ranged from 21 to 52 years; the median follow-up was 33 years. Forty-four percent (27/61) were currently experiencing low-back pain, 57% (35/61) had back pain in the last year. Fifty-three percent (33/62) were using medication. Fifteen percent (9/62) had undergone repeat lumbar surgery, however, only 5% (3/62) required surgery as a late sequela (more than 10 years postoperatively). Forty-two percent (14/33) had lumbar spinal stenosis, but only 15% (5/33) had dural tube measurements less than 100 mm2. Segmental instability above the fusion was present in 45% (15/33). There was a significant correlation between segmental instability and lumbar spinal stenosis (r = .57, P < .01). Neither radiographic condition correlatied with symptoms, however. Patients fused for spondylolysis and spondylolisthesis were likely to report incidence of pain and reported less severe pain than patients fused for other reasons (P < .01 and < .10, respectively). There was no significant difference in the disability assessments between these surgical subgroups. Although patients after lower lumbar fusion report more pain than the general population and have more radiographic evidence of instability and stenosis than expected for the general population, they are generally doing well and are satisfied with the results of their surgery.