Wai et al. 1 developed indexes that identified significant fibrosis in patients with chronic hepatitis C. These indexes, including aspartate aminotransferase (AST) and platelets, had good discriminative power, as shown by areas under the receiver operating characteristic curve (AUROC) of 0.82 for formula 1 predicting fibrosis, 0.92 for formula 2 predicting cirrhosis, 0.83 for AST-Platelets Ratio Index (APRI) for fibrosis, and 0.90 for cirrhosis. We also validated a fibrosis index (Fibrotest; Biopredictive, Houilles, France, US Patent Application Serial No. 09/687,459) with high predictive values. [2][3][4] We sought to compare these indices by using data collected retrospectively in 323 patients from our original population with complete biochemical data. 2 The prevalence of significant fibrosis (F2-F4) was 41%, and cirrhosis (F4) was 13%. The mean value (SE) for AST expressed in ULN was 1.71 (0.10) and platelets count 192 (3) 10 9 /L. AUROCs for significant fibrosis were 0.75 (0.03) for formula 1 and 0.74 (0.03) for APRI versus 0.83 (0.02) for Fibrotest (P ϭ 0.03 vs. formula 1 and P ϭ 0.02 vs. APRI), 5 suggesting that the latter has greater discriminative power. The AUROCs for cirrhosis were 0.82 (0.04) for formula 2 and 0.80 (0.04) for APRI versus 0.92 (0.03) for Fibrotest (P ϭ 0.04 vs. formula 2 and P ϭ 0.02 vs. APRI), suggesting that the latter has greater discriminative power. There was a continuous, almost linear, relationship between Fibrotest and fibrosis stage, with significant differences between stages that were not observed for the Wai 1 indexes (Fig. 1).