The NIDDK is conducting a research study called, "Combination of Alpha Interferon with Long Term Ribavirin Therapy for Patients with Chronic Hepatitis C" (98-DK-0003). Patients participating in it are receiving interferon-alpha in addition to an antiviral medication called ribavirin. Researchers at the NIMH intend to study patients to learn more about how different medications can influence mood, thoughts and behavior.