BACKGROUND: Hospital mortality rates are higher among patients with sepsis-associated acute kidney injury (SA-AKI) than among patients with sepsis. However, the pathogenesis underlying SA-AKI remains unclear. We hypothesized that the source of infection affects development of SA-AKI. We aim to explore the relationship between the anatomical source of infection and outcome in patients with SA-AKI. METHODS: Between January 2013 and January 2018, 113 patients with SA-AKI admitted to our Emergency Center were identified and divided into two groups: those with pulmonary infections and those with other sources of infection. For each patient, we collected data from admission until either discharge or death. We also recorded the clinical outcome after 90 days for the discharged patients. RESULTS: The most common source of infection was the lung (52/113 cases, 46％), followed by gastrointestinal (GI) (25/113 cases, 22.1％) and urinary (22/113, 19.5％) sources. Our analysis showed that patients with SA-AKI had a significantly worse outcome (30/52 cases, P<0.001) and poorer kidney recovery (P=0.015) with pulmonary sources of infection than those infected by another source. Data also showed that patients not infected by a pulmonary source more likely experienced shock (28/61 cases, P=0.037). CONCLUSION: This study demonstrated that the source of infection influenced the outcome of SA-AKI patients in an independent manner. Lung injury may influence renal function in an as-yet undetermined manner as the recovery of kidney function was poorer in SA-AKI patients with a pulmonary source of infection.