Background: Spontaneous bacterial peritonitis (SBP) is one of the common and lethal infections in patients with liver cirrhosis. It is frequently complicated with acute kidney injury (AKI), which makes the condition worse with higher mortality. Urinary markers may have potential clinical importance in this setting. Aim: To assess the utility of urinary neutrophil gelatinase-associated lipocalin (uNGAL), in early detection of AKI in patients with liver cirrhosis with SBP, and evaluating its prognostic role in the detection of the outcome and mortality in those patients. Materials and Methods; group (1): 30 patients hospitalized with cirrhotic liver and SBP and group(2): 30 patients with liver cirrhosis without SBP. AKI was defined according to Acute Kidney Injury Network (AKIN) criteria. uNGAL was measured. Results: AKI patients(n=21) had higher uNGAL levels compared to patients without AKI (n=9), (7.55 ± 3.20 vs. 1.23 ± 0.78ng/ml‚ P=0.001), patients with AKI persisted more than 3 days had higher uNGAL levels at diagnosis of SBP in comparison to patients who less than 3 days AKI (8.88 ± 1.51vs.4.37 ± 1.95ng/ml; P = 0.005), both model of end stage liver disease-sodium (MELD Na) and uNGAL level at diagnosis of SBP are an independent predictor of 3-months mortality. Conclusion: In patients with liver cirrhosis and SBP, measurement of uNGAL at time of SBP diagnosis can diagnose AKI and predict important clinical outcome, as persistency of AKI and three months mortality.