Patients 18 years of age and older with chronic HCV infection who require a liver transplant for end-stage liver disease or a kidney transplant for kidney failure may be eligible for this study. Liver transplant patients are recruited from the Inova Fairfax Liver Transplant Center in Fairfax, Virginia, and from the Georgetown University Medical Center Liver Transplant Institute in Washington, D.C. Kidney transplant patients are recruited from the Transplantation Branch of the National Institute of Diabetes and Digestive and Kidney Diseases.