Infection with HCV is common in patients infected with HIV owing to similar routes of transmission. The cellular immunosuppression caused by HIV infection appears to lead to an increased HCV plasma load, more progressive liver disease, and, in patients with chronic hepatitis C, increased mortality. Ribavirin treatment combined with IFN has shown improved sustained virologic response rates over IFN monotherapy. PEG-IFN, a chemically modified formulation of IFN, circulates for a much longer time in the blood than the parent compound. Pharmacokinetic and pharmacodynamic data suggest that PEG-IFN injected weekly would have the potential for superior efficacy as compared with IFN injected 3 times per week. The efficacy and safety profiles of combination therapy with PEG-IFN and ribavirin are not well known. This study will compare combination therapy consisting of PEG-IFN and ribavirin with that of IFN and ribavirin.