Abstract: Objective To investigate the diagnostic value of cystain C (SCys-C) in contrast associated acute kidney injury (AKI) after transcatheter closure for children with congenital heart disease. Methods There were 128 children with congenital heart disease (interventricular septal defect or patent ductus arteriosus) underwent transcatheter closure in West China Second University Hospital during 2013. Blood urea nitrogen (BUN), serum creatinine (SCr) and SCys-C were examined before surgery and at 24 and 48 h after surgery. The incidence of AKI was calculated. The children were divided into two groups according to glomerular filtration rate: AKI group (renal function stage 1, renal function stage 2 subgroups) and non-AKI group. Differences in renal function indexes and SCys-C were compared between AKI group ( n=16) and non-AKI group ( n=112), renal function stage 1 and stage 2 subgroups. ROC curve analysis was used to calculate the cut-off value of SCys-C in the diagnosis of AKI . Results The levels of SCr and SCys-C in AKI group were significantly higher than those in non-AKI group ( P<0.05). However, there was no significant difference in BUN between the two groups ( P>0.05). Only SCys-C had a significant difference between renal function stage 1 and stage 2 subgroups ( P<0.05). The cut-off value of 24 h SCys-C in the diagnosis of AKI was 1.055 mg/L according to area under curve (AUC). AUC indicated that AKI could be diagnosed earlier with SCys-C than SCr ( P<0.05). Conclusion The contrast agent could increase the CM(155.3mmrisk of child AKI after transcatheter closure for congenital disease children.SCys-C is an important index for this CM)