Context: Treatment of chronic hepatitis C virus (HCV) infection in human immunodeficiency virus (HIV)-infected patients is a growing concern. Most data on the virologic efficacy and safety of the combination of peginterferon alfa-2b and ribavirin in coinfected patients come from uncontrolled studies. Objective: To study the safety and efficacy of peginterferon alfa-2b plus ribavirin vs standard interferon alfa-2b plus ribavirin in HIV-HCV coinfected patients. Design and Settings: A multicenter,randomized,parallel-group,open-label trial. Patients were enrolled from February 2000 to February 2002 and followed up for 72 weeks. Patients: Four hundred twelve HIV-HCV coinfected patients with detectable serum HCV-RNA,abnormal liver histology,a CD4 cell count of at least 200 ×106/L,and stable plasma HIV-RNA. Intervention: Treatment with ribavirin 400 mg twice a day,orally,plus either peginterferon alfa-2b (1.5 μg/kg subcutaneous injection once a week) or standard interferon alfa-2b (3 million units of subcutaneous injection 3 times a week) for 48 weeks. Main Outcome Measures: Sustained virologic response,defined by undetectable serum HCV-RNA at week 72. Results: More patients had sustained virologic responses in the peginterferon group than in the standard interferon group (27%vs 20%,P=.047). This difference between the treatments was found in patients with HCV genotype 1 or 4 infection (17%for peginterferon vs 6%for standard interferon,P=.006) but was not found in patients with HCV genotype 2,3,or 5 (44%for peginterferon vs 43%for standard interferon,P=.88). Together,a decline in HCV-RNA of less than 2 log10 from baseline and detectable serum HCV-RNA at week 12 predicted 99%of treatment failures. Histologic activity diminished and fibrosis stabilized in virologic responders. The 2 regimens showed similar tolerability although dose modifications for clinical and biological events were more frequent with peginterferon. Eleven cases of pancreatitis or symptomatic hyperlactatemia were observed,all in patients receiving didanosine-containing antiretroviral regimens. Conclusion: In combination with ribavirin,treatment with peginterferon alfa-2b is more effective than standard interferon alfa-2b for HCV infection in HIV-infected patients. Context: Treatment of chronic hepatitis C virus (HCV) infection in human immunodeficiency virus (HIV) -infected patients is a growing concern. Most data on the virologic efficacy and safety of the combination of peginterferon alfa-2b and ribavirin in coinfected patients come from Objective: To study the safety and efficacy of peginterferon alfa-2b plus ribavirin vs standard interferon alfa-2b plus ribavirin in HIV-HCV coinfected patients. Design and Settings: A multicenter, randomized, parallel-group, open-label trial Patients were enrolled from February 2000 to February 2002 and followed up for 72 weeks. Patients: Four hundred twelve HIV-HCV coinfected patients with detectable serum HCV-RNA, abnormal liver histology, a CD4 cell count of at least 200 × 106 / L , and stable plasma HIV-RNA. Intervention: Treatment with ribavirin 400 mg twice a day, orally, plus either peginterferon alfa-2b (1.5 μg / kg subcutaneous injection once a week) or standard interferon alfa-2b n Out of Quantities HCV RNA at Week 72. Results: More patients had sustained virologic responses in the peginterferon group than in standard interferon This difference between the treatments was found in patients with HCV genotype 1 or 4 infection (17% for peginterferon vs 6% for standard interferon, P = .006) but was not found in patients with HCV genotype 2, 3, or 5 (44% for peginterferon vs 43% for standard interferon, P = .88). Together, a decline in HCV-RNA of less than 2 log10 from baseline and detectable serum HCV- RNA at week 12 predicted 99% of treatment failures. Histologic activity diminished and fibrosis stabilized in virologic responders. The 2 regimens were similar tolerability although dose modifications for clinical and biological events were more frequent with peginterferon. Eleven cases of pancreatitis or symptomatic hyperlacta temia were observed, all in patients receiving didanosine-containing antiretroviral regimens. Conclusion: In combination with ribavirin, treatment with peginterferon alfa-2b is more effective than standard interferon alfa-2b for HCV infection in HIV-infected patients.