Abstract: Objective To investigate the clinical significance of serum heart fatty acid binding protein (HFABP) in acute kidney injury (AKI).Methods According to the diagnostic and staging criteria of 2012 KDIGO guidelines, 92 patients with clinically diagnosed acute kidney injury were collected and divided into AKI stage Ⅰ group (53 cases), stage Ⅱ group (26 cases), stage Ⅲ group (13 cases). Thirty cases of chronic kidney disease (CKD, stage Ⅰ-Ⅳ) and 30 cases of healthy physical examination at the same time served as control group. The basic data (sex, age, primary disease, etc.) of the patients were collected. The fasting 24-h blood specimens were collected after the diagnosis. The biochemical analyzer was used to determine the serum creatinine, Cystatin C and other biochemical indicators. The HFABP content was detected by enzyme-linked immunosorbent assay. The receiver operating characteristic (ROC) and the area under the curve (area under curve, AUC) were used to analyze the early diagnostic value of HFABP for AKI. The optimal truncation value of HFABP and the sensitivity and specificity of HFABP in the diagnosis of AKI were found according to the ROC curve.Results As compared with the normal control group, the levels of HFABP in the AKI Ⅰ group and the AKI Ⅱ+Ⅲ group were significantly increased (P<0.05), and significantly increased with the progress of AKI (P<0.05). As compared with the CKD group, the levels of HFABP in AKI Ⅰ group were slightly lower (P>0.05), and those in AKI Ⅱ+Ⅲ group were significantly higher than those in CKD group (P<0.05). As compared with the normal control group, the levels of Cys C in AKI Ⅰ group and AKI Ⅱ+Ⅲ group were significantly increased (P<0.05). As compared with the CKD group,the level of Cys C in group AKI Ⅰ was slightly lower than that in group CKD (P>0.05).The levels of Cys C in AKI Ⅱ+Ⅲ stage group were slightly increased (P>0.05). The correlation analysis showed that serum HFABP and Cys C levels were positively correlated (r=0.821, P<0.05). In AKI Ⅰ group, the optimal cutoff value of serum HFABP for diagnosis of AKI was 15.16 ng/ml, and the AUC of serum HFABP and Cys C for diagnosis of AKI was 0.771 and 0.733 respectively. The optimal cut-off value of serum HFABP in AKI Ⅱ+Ⅲ group was 20.12 ng/ml, and the AUC of serum HFABP and Cys C was 0.935 and 0.918 respectively in AKI Ⅱ+Ⅲ group.Conclusions HFABP is an effective biomarker for detection of AKI, and it is important for the diagnosis of AKI.