This proposal for the Mentored Clinical Research Award (K-23) is to provide supervised experience in patient oriented clinical research. The candidate is an Associate Professor of Medicine in the Division of Gastroenterology and Hepatology at Virginia Commonwealth University Health System/Medical College of Virginia campus (VCUHS/MCV). His career goals are: (1) to be an outstanding clinician and (2) to be a leading scientist in patient-oriented research in liver disease. During the period of support, the applicant will be primarily mentored by Dr. Arun J. Sanyal with support from other faculty from Hepatology (Dr. Mitchell L. Shiffman), Infectious Disease (Dr. Evelyn Fisher), Biostatistics (Dr. Chris Gennings), and Quality Health Care (Dr. Wally Smith). Effective therapy for human immunodeficiency virus (HIV) infection has markedly prolonged survival in infected individuals. As a result, other comorbid conditions in these patients are becoming more clinically important. Approximately 30% of HIV infected patients are also infected with hepatitis C virus (HCV) which is now the leading co-morbid disease in HIV-infected individuals. The histologic severity and natural history of HCV has been reported to be accelerated in those co-infected with HIV. It is hypothesized that: 1) the severity and progression of hepatic fibrosis in patients with HIV-HCV co-infection is directly related to the immunologic competence of the individual, and 2) the virologic response to anti-HCV treatment is directly related to the degree of immunologic competence. These will be tested by the following specific aims: 1) to perform a longitudinal prospective cohort study of subjects with HIV-HCV co-infection and to define the change in the distribution of hepatic fibrosis scores and the relationship between these changes and the immunologic status, and 2) to prospectively define the relationship between the immunologic status and the sustained virologic response to anti-HCV therapy. The institution and departmental environment as well as the facilities and resources are excellent for career development in academic medicine. The K-23 award will protect this candidates time and help him mature into a senior investigator in Hepatology.