Objective To investigate the predictive value of preprocedural cystatin C level for contrast-in-duced acute kidney injury (CI-AKI) and poor long-term outcome after cardiac catheterization. Methods One thou-sand one hundred and fifty-four patients underwent cardiac catheterization were enrolled in Guangdong general hos-pital. The level of serum cystatin C was determined at 24 hours pre-operation. A 2-year follow up was performed for each patient. Preprocedural cystatin C level was compared between patients with or without CI-AKI. The cystatin C quartiles were compared between patients with incidence of CI-AKI and patients with adverse in-hospital outcomes. Analyses of the receiver operating characteristic curves (ROC) were performed to evaluate the predictive value and cutoff level of cystatin C level for CI-AKI. The log-rank test and Cox regression analyses were also performed to in-vestigate the correlation between cystatin C level and poor long-term outcomes. Results CI-AKI occurred in 42 patients (3.6%). The cystatin C level was significantly higher in the CI-AKI group than that in the non-CI-AKI gu-oup (1.76 ± 1.05 vs 1.20 ± 0.50 mg/L, P=0.001). Patients with higher cystatin C level also had higher risk of CI-AKI and adverse in-hospital outcomes. ROC and Youden index showed that 1.3 mg/L cystatin C of was a fair dis-criminator for CI-AKI, but not significantly different from the Mehran CI-AKI score (AUC, 0.75 vs 0.76, P =0.874). After adjusting for other known CI-AKI risk factors, cystatin C level over 1.3 mg/L remained significantly associated with CI-AKI. During the long-term follow-up , the patients with cystatin C level over 1.3 mg/L were at a higher risk of all-cause mortality and MACEs (P < 0.001). Concusions A preprocedural cystatin C level over 1.3 mg/L was a good predictor of CI-AKI and poor long-term outcomes after cardiac catheterization.