Acute kidney injury (AKI) in the elderly is characterized by high mortality. The objective of this study is to identify the causes of death in the elderly with AKI. This is a prospective cohort study with a descriptive purpose which was carried out during the period from January 2009 to December 2014 in the Department of Nephrology-Internal Medicine of Treichville University Hospital. The diagnosis of AKI was made on the basis of serum creatinine (SCr) values determined during hospitalization, according to KDIGO classification. Our study involved 107 elderly aged 65 and older with AKI. The hospital mortality rate was 46.7% (50/107). The average age of deceased patients was 71.8 ± 7 years with extremes of 65 and 90 years. We observed a male predominance with a sex ratio (41/9) of 4.55. AKI on admission was in Stage 1 in 16% of cases, in Stage 2 in 24%, and in Stage 3 in 60% cases. SCr was normal in 8%, the AKI was in Stage 1 in 34% (P = 0.09), Stage 2 in 18% (P = 0.001), and Stage 3 in 40% (P = 0.0001). AKI in deceased patients was organic in 36% of cases, obstructive in 30%, and functional in 6%. The etiologies of AKI were infections (46%), cancer (18%), benign tumors of the urinary tract (12%), malignant hypertension (6%), decompensated heart disease (6%), and drugs (6%). The main causes of death were sepsis (28%), cardiovascular disease (22%), severe renal failure (20%), pelvic cancers (16%), and liver failure (12%). All patients with cancer (P = 0.001) or HIV infected (P = 0.009) died. Sixty-eight percent of deaths occurred the 1st week. Death was earlier by sepsis and cardiovascular disease than by cancer. Mortality is high in the elderly. The main causes of death were sepsis, cardiovascular disease, renal failure, pelvic cancer, and liver failure.