STUDY DESIGN: Retrospective chart review. OBJECTIVES: To investigate the extent of renal deterioration in patients with spinal cord injury (SCI) and to identify risk indicators associated with renal deterioration. SETTING: Clinic for Spinal Cord Injuries, Rigshospitalet, Hornbæk, Denmark. METHODS: This study included 116 patients admitted to our clinic with a traumatic SCI sustained between 1956 and 1975. Results from renography and 51 Cr-EDTA plasma clearance were collected from medical records from time of injury until 2012, and the occurrence of renal deterioration was analysed by cumulative incidence curves. The impact of demographics, neurological level and completeness of SCI, urinary tract stones, dilatation of the upper urinary tract (UUT) and bladder-emptying methods were analysed with Cox proportional hazard ratios. RESULTS: The bladder-emptying methods used for the longest period were reflex triggering (63%), bladder expression (22%), indwelling catheter (5%), normal voiding (4%), ileal conduit (3%) and clean intermittent catheterisation (2%). The cumulative risk of moderate renal deterioration (functional distribution outside 40-60% on renography or relative glomerular filtration rate (GFR) ≤75% of expected according to age and gender) was 58%. The cumulative risk of severe renal deterioration (functional distribution outside 30-70% on renography or relative GFR≤51%) was 29% after 45 years postinjury. Only dilatation of UUT and renal/ureter stone requiring removal significantly increased the risk of moderate and severe renal deterioration. CONCLUSION: Renal deterioration occurs at any time after injury, suggesting that lifelong follow-up examinations of the renal function are important, especially in patients with dilatation of UUT and/or renal/ureter stones.