Purpose: To determine the long-term outcome after fusion for adolescent idiopathic scoliosis in terms of degenerative disc findings diagnosed using MR imaging and to elucidate the clinical consequences.Material and Methods: Thirty-two patients with adolescent idiopathic scoliosis, who had undergone spinal fusion using Harrington rods to the lower lumbar spine with one or two unfused discs below the fusion, were re-examined 25 years after the fusion. The re-examinations included validated questionnaires, clinical examination, full standing frontal and lateral radiographs and MR examination of the lower lumbar region. Curve size and degenerative findings on MR images were evaluated by two unbiased radiologists, blinded to the clinical findings. A matched control group of 32 persons without scoliosis was subjected to the same examinations.Results and Conclusion: There were significantly more degenerative disc changes (p<0.0001), disc height reduction (p=0.0010) and end-plate changes (p<0.0001 for both upper and lower end-plates) in the lowest unfused disc in the patient group compared with the control group. The MR findings in the lowest unfused disc, but not the one above, in the patient group correlated to lumbar pain intensity as well as to the diminished lumbar lordosis.