Background Epidemiological data on Acute Kidney Injury (AKI) from low-income countries is sparse. The aim of this study was to establish the incidence, severity, aetiology, and outcomes of community-acquired AKI in Malawi. Methods We conducted a prospective observational study of general medical admissions to a tertiary hospital in Blantyre between 27th April and 17th July 2015. All patients were screened on admission with a serum creatinine; those with creatinine above laboratory reference range were managed by the nephrology team. Hospital outcome was recorded in all patients. Results Eight hundred ninety-two patients were included; 188 (21 · 1%) had kidney disease on admission, including 153 (17 · 2%) with AKI (median age 41 years; 58 · 8% HIV seropositive). 60 · 8% of AKI was stage 3. The primary causes of AKI were sepsis and hypovolaemia in 133 (86 · 9%) cases, most commonly gastroenteritis (n = 29; 19 · 0%) and tuberculosis (n = 18; 11 · 8%). AKI was multifactorial in 117 (76 · 5%) patients; nephrotoxins were implicated in 110 (71 · 9%). Inpatient mortality was 44 · 4% in patients with AKI and 13 · 9% if no kidney disease (p