Medical guidelines forinterferon-α2a or-α2b(IFN-α) treatment of chronic hepatitis C virus(HCV) infection depend upon baseline liver histology. Abetter long-term response to IFN-α therapy correlates with less inflammation and absenceof cirrhosis. It has been suggested that the presence ofcirrhosis in patients with chronic hepatitis C virusinfection may be predicted based on an AST/ALT ratio ≥1. This study was designed todetermine if the presence of cirrhosis can be predictedin patients with chronic HCV infection by such a ratio.Seventyseven patients, including 23 cirrhotics, withchronic HCV infection were studied. Serum ALT, AST, andHCV-RNA levels and hepatic activity index (HAI),reflecting histologic inflammation in all liverbiopsies, were assessed. AST/ALT ratios and mean ALT,AST, and HCV-RNA were determined for both cirrhoticand noncirrhotic patients. HAI was correlated with ALT,AST, and HCV-RNA levels, the latter determined byquantitative RT-PCR. The likelihood ratio (LR) and positive predictive value of an AST/ALT ratio≥1 for cirrhosis was 7.3 and only 77% , respectively.In cirrhotics vs noncirrhotics, there were nosignificant differences between mean serum ALT (149± 28 vs 176 ± 17 units/liter), AST (139± 28 vs 102 ± 8 units/liter), or HCV-RNAlevels (589,160 ± 147,053 vs 543,915 ±75,497 copies/ml), respectively. There was asignificant, but clinically weak, correlation between serum ALT and HAI (r =0.234), and none between HAI and either serum AST orHCV-RNA levels. Our results support the need for a liverbiopsy prior to treatment of chronic HCV infection, since the AST/ALT ratio fails to predictaccurately the presence of cirrhosis.