Objective: To investigate the serum concentration of neutrophil gelatinase-associated lipocalin (NGAL) in children with acute heart failure (AHF) and evaluate the diagnosis value of it in worsening renal function (WRF) in children with AHF during hospitalization. Methods: Thirty patients with AHF and 20 healthy children without AHF were enrolled in this study in our hospital from January 2017 to December 2017. The cardiac function was assessed by echocardiographic in all subjects. Blood urea nitrogen (BUN), creatinine, NGAL concentrations and glomerular filtration rate were measured at admission (Day 1) and 72 h after admission (Day 3). Results: Serum NGAL concentrations was significantly higher in children with AHF than the children without AHF [(12.5±11.0) vs (4.5±3.0) μg/L, P<0.001]. Seventeen (56.6%) children suffered WRF during hospitalized within 72 h. Serum NGAL concentrations was significantly higher in children accompanied WRF than those without WRF [(38±10) vs (5.0±7.2) μg/L, P<0.001]. When the serum NGAL concentrations cutoff value was >27.5 μg/L, NGAL concentration can diagnosis the WRF in AHF children with a sensitivity of 87%, specificity of 68%, and the area under the curve (AUC) of 0.869 (95% CI 0.783–0.890, P<0.001), which was higher than serum BUN (AUC=0.669) and e-GFR (AUC=0.714). Conclusion: Serum NGAL has a good ability to diagnose renal function deterioration in hospitalized children with AHF and can be used as a marker of renal impairment in children with AHF.