Acute Kidney Injury (AKI) is increasingly common in people over 65 years of age, but its causes and management are poorly described. The purpose of this study was to describe the causes, management and prognosis of patients over 65 hospitalised for severe acute kidney injury (AKI) in all departments of a tertiary centre. Method: The prospective IRACIBLE (IRA: AKI in French; CIBLE: target in French) cohort included 480 patients hospitalised at a university hospital over 18 months for severe AKI or subgroup of AKIN3 (Acute Kidney Injury Network classification) defined by an acute creatinine increase > 354 μmol/L or managed with acute renal replacement therapy (RRT). The history, aetiology of AKI, management, and prognosis were compared in three age groups: < 65, 65-75, and > 75 years. Results: The study population included 480 subjects (73% men) with a median body mass index (BMI) of 26.6 kg/m2 [23.3, 30.9], 176 (37%) diabetic patients, 124 (26%) patients < 65 years, 150 (31%) 65-75 years and 206 (43%) > 75 years. Increasing age class was associated with more comorbidities, a significantly lower median estimated glomerular filtration rate (eGFR) 6 months before inclusion (82; 62; 46 ml/min/1.73 m2, p < 0.05) and aetiology of AKI, which was more often obstructive (12%; 15%; 23%, p = 0.03) or part of a cardio-renal syndrome (6%; 9%; /15%, p = 0.04). Older patients were less often managed in the intensive care unit (54%; 47%; 24%, p < 0.0001), were less frequently treated by RRT (52%; 43%; 31%, p < 0.001) and received fewer invasive treatments (6%; 9%; 22%, p < 0.0001). Older survivors returned home less often (80%; 73%; 62%, p = 0.05) in favour of transfers to rehabilitation services (10%; 13%; 22%) with higher mortality at 3 months (35%; 32%; 50%, p < 0.0001). Conclusion: Older patients hospitalised for severe AKI have a specific profile with more comorbidities, lower baseline renal function, an aetiology of AKI of mainly extra-parenchymal causes and a complex pathway of care with an overall poor prognosis.