Objective: Hepatitis C virus (HCV) is one of the most common blood-borne infections in the US. The cost burden of HCV to third party payers has not been widely investigated using administrative data. We analyzed retrospective insurance claims to estimate total, all-cause resource utilization and costs among managed care enrollees with chronic HCV compared to similar subjects without HCV. Methods: A large US claims database was analyzed from January 1, 2002 through December 31, 2006. Inclusion criteria were: =1 diagnosis of chronic HCV (ICD-9 070.44, 070.54, 070.70, or 070.71); no evidence of hepatitis B; =12 months of continuous plan enrollment post-diagnosis. Per patient use and costs of all medical services and prescription drugs utilized over a 12-month period post-diagnosis were evaluated. Outcomes were also assessed in controls without HCV matched (1:1) on age, gender, and length of plan enrollment. Results: A total of 20,662 patients met all inclusion criteria. Mean age was 49 years and 61% were male. Total costs were $20,830 per HCV patient, compared to $4,673 per control (P<0.0001). Hospitalization was seen in 24% of HCV patients compared to 7% of controls (P<0.0001), with mean inpatient costs of $5765 and $1,031 per patient, respectively (P<0.0001). Patients with HCV had significantly higher (P<0.0001) prescription costs compared to controls ($6178 vs. $1097), as well as increased use and costs of other medical services, including office visits (23 vs. 11 visits; $2112 vs. $1036), other ancillary services ($4800 vs. $1301), emergency care (32% vs. 14% with =1 admission; $387 vs. $114), and laboratory tests ($741 vs. $110). Conclusion: Costs incurred by payers for patients with HCV are more than four times the costs attributable to individuals without HCV. Pharmacy and inpatient services are drivers of these costs. Health plans should be aware of heightened costs for enrollees with HCV when considering formulary access for treatments.