Sixty naive patients with HIV and confirmed hepatitis C who are co-enrolled in another AACTG antiretroviral study that involves the testing of HAART (Highly Active Antiretroviral Therapy) are entered on this prospective study. Patients who are defined as naive have never received specific, active antiretroviral agents that sustain viral suppression below the limit of detection (500 copies/ml) or have received those agents for only a very limited time. HAART is defined as therapy which is likely to result in HIV-1 RNA plasma levels less than 500 copies/ml for at least 16 weeks. Plasma is collected and evaluated during the study for additional quantitative measurements: Hepatitis C virus (HCV) by HCV RNA PCR and HIV-1 RNA levels. All evaluations for HIV-1 RNA are obtained from the co-enrolled study at the following time points: Pre-entry, entry, at least 2 measurements before Week 16, Week 16, and at least 1 measurement after Week 16.