['Serum fibrosis marker levels during the lead-in treatment phase of patients enrolled in the Hepatitis C Antiviral Long-term Treatment against Cirrhosis (HALT-C) trial were determined.', 'Week 0, 24, 48, and 72 serum samples were analyzed for YKL-40, tissue inhibitor of matrix metalloproteinase-1, amino-terminal peptide of type III procollagen (PIIINP), and hyaluronic acid (HA) levels. All 456 chronic hepatitis C (CHC) patients received peginterferon alfa 2a and ribavirin for 24 to 48 weeks.', 'Mean age was 49.2 years, 71% were male, and 39% had cirrhosis. Lower pretreatment serum YKL-40, tissue inhibitor of matrix metalloproteinase-1, PIIINP, and HA levels were associated significantly with week-20 virologic response (P < .0001). In multivariate analysis, non-1 CHC genotype, non-black race, prior interferon monotherapy, and lower baseline serum aspartate aminotransferase/alanine aminotransferase levels and log(10)YKL-40 levels were associated independently with week-20 virologic response. Statistically significant declines in all marker levels were observed at week 72 compared with baseline in the 81 patients with a sustained virologic response, but not in the 72 patients with breakthrough or relapse. At weeks 24 and 48, significant increases were observed in serum PIIINP and HA levels compared with baseline in virologic responders and nonresponders (P < .0001).'] Do serum fibrosis marker levels decrease after successful antiviral treatment in chronic hepatitis C patients with advanced fibrosis?