3. Methodology: Patients will be asked to participate in a prospective study in which they will be monitored during the course of IFN therapy for symptoms of depression and for biochemical changes measured in their blood. 120 HCV patients initiating IFN therapy will be recruited (3/month for 40 months) from the Portland VA and the Long Beach VA Medical Centers. Following baseline assessments, subjects will be followed every 2 weeks for a period of 4 months. The development of major depression, depressive symptoms, and related IFN-induced side effects will be monitored using rating scales. For genetic and biochemical measures, blood samples will be collected prior to and during IFN therapy. Patients will be tested for certain genetic polymorphisms.