BACKGROUND: We evaluated the diagnostic performance of a newly developed Elecsys Anti-HCV II assay in Korean patients. METHODS: A total of 500 serum samples (400 antibody to hepatitis C virus [anti-HCV]-negative and 100 anti-HCV-positive samples) were collected after testing with Elecsys Anti-HCV assay (Roche Diagnostics, Germany). All the samples were tested for anti-HCV by using Vitros Anti-HCV (Ortho-Clinical Diagnostics, UK) and Elecsys Anti-HCV II (Elecsys II) (Roche Diagnostics, Germany) assays. Specimens that were found to be positive or negative in all the 3 assays were considered positive or negative for anti-HCV, respectively, and medical records of the patients, including results of previous HCV tests, were reviewed to determine the final results for anti-HCV when there were discrepancies among the results of the anti-HCV assays. RESULTS: Discrepancies between the results of the 3 anti-HCV assays were found for 4 of the 500 samples (0.8%). Sensitivity/specificity values for Elecsys II were 98.0%/100.0%, and the corresponding values for Elecsys and Vitros assays were 100.0%/100.0% and 100.0%/99.5%. Concordance rates between the results of any 2 of the 3 assays were equal or greater than 99.2%, with a kappa coefficient of 0.98 or greater (P < 0.0001). CONCLUSIONS: Sensitivities and specificities of the anti-HCV assays evaluated in this study were high enough for being used in clinical laboratories, and the results of the 3 assays showed good agreement. However, samples for which weak-positive results were obtained would need to be retested, considering the discrepancies between the anti-HCV assays.