Previous reports suggest cryoglobulinemia might influence the hepatitis C virus (HCV) infection clinical course and treatment response but this association has not been thoroughly evaluated. We aimed to assess the relationship between cryoglobulinemia and sustained viral response (SVR) in patients treated for HCV infection. We included patients with HCV infection treated from January 2003 through December 2006. Biochemical analyses, detection cryoglobulinemia, and liver biopsies were performed prior to treatment. Genotype 1 or 4 infections received Peg-interferon (IFN) alpha-2a or -2b for 48 weeks; genotypes 2 or 3 received IFN alpha for 24 weeks. All patients also received ribavirin. Of 329 enrolled patients, 242 (73%) were male and the median age was 43 years. Cryoglobulinemia was detected in 196 (59.6%) patients; liver biopsy was performed in 301. Multivariate analysis showed an association of cryoglobulinemia with severe active necroinflammation (A3) (adjusted odds ratio [AOR] = 9.48; 95% confidence interval [CI]: 1.50-59.92) and rheumatoid factor (RF) level (AOR = 1.01; 95% CI: 1.00-1.02). Variables associated with advanced fibrosis were age, aspartate aminotransferase and alkaline phosphatase levels, alcohol use, and presence of diabetes. Variables independently associated with SVR were cryoglobulinemia (AOR = 2.33, 95% CI: 1.26-4.32), absence of cirrhosis (AOR = 4.5, 95% CI: 1.4-14.80), and RF level (AOR = 1.008, 95% CI: 1.001-1.014). Our findings suggest cryoglobulinemia is associated with severe necroinflammatory activity in HCV-infected patients. We also provide the first evidence for an association between cryoglobulinemia and higher SVR rates, highlighting its potential role as a prognostic factor for treatment response.18e91-8