OBJECTIVES: Estimate the incremental impact of HCV on health care costs and events using claims data from a large U.S. health insurance provider. METHODS: 1:1 matched samples of newly diagnosed HCV and non-HCV patients were identified using propensity scoring techniques.  Costs and events were measured over the first post-diagnosis year for HCV patients.  Non-HCV patients were assigned an index date corresponding to the index date of their matched HCV patient.     RESULTS: A total of 60,806 HCV patients were identified using 6 years of data based on two or more HCV diagnoses or a single diagnosis combined with an HCV-related prescription.   Further screening for at least one year of eligibility prior to index date and pre-existing HIV, hepatitis B, cirrhosis, liver cancer or a liver transplant resulted in an initial HCV population of 9191 patients.  An additional 410,605 non-HCV patients were identified with similar criteria during their first year of eligibility.  Both samples were used to estimate a parsimonious logistic propensity score model of HCV diagnosis.  A total of 9,129 HCV patients were matched with non-HCV patients [99.3% match rate]. The incremental cost of HCV was estimated at +$17,307 over the first post-index year.  HCV doubled the likelihood of hospitalization or a future diagnosis of depression and dramatically increased the risk of cirrhosis, liver cancer and liver transplantation were increased dramatically by an HCV infection [OR = 62.4, 26.4 and 44.4 respectively].  CONCLUSIONS: The incremental cost of HCV in the first post-index year is quite high due in part to the increased risk of cirrhosis, liver cancer and transplantation. A longer term study is needed to investigate economic consequences over time for these newly recognized HCV patients.