Objective: To estimate the direct and indirect costs of the hepatitis C virus (HCV) in the United States in 1997. Design Aggregation and analysis of national data sets collected by the National Center for Health Statistics, the Health Care Financing Administration, and other government bureaus and private firms. To estimate costs, we used the human capital method, which decomposes costs into direct categories, such as medical expenses, and indirect categories, such as lost earnings and lost home production. We consider HCV that results in chronic liver disease separate from HCV that results in primary liver cancer. Results: We estimate $5.46 billion as the cost of HCV in 1997. Costs are split as follows: 33% for direct and 67% for indirect costs. Hepatitis C virus that results in chronic liver disease contributes roughly 92% of the costs, and HCV that results in primary liver cancer contributes the remaining 8%. The total estimate of $5.46 billion is conservative, because we ignore costs associated with pain and suffering and the value of care rendered by family members. Conclusions: To our knowledge, only one estimate of the annual costs of HCV in the 1990s has appeared in the literature, $0.6 billion. However, that estimate was not supported by an explanation of the methods. Our estimate, which relies on detailed methods, is nearly 10 times the original estimate. Our estimate of $5.46 billion is on a par with the cost of asthma ($5.8 billion 1994).