OBJECTIVES: To estimate resource utilization and direct medical cost of chronic hepatitis C (CHC) from a Thai payer perspective. METHODS: Medical records of CHC patients diagnosed during 2003-2006 at 5 major tertiary-care hospitals in Thailand were retrospectively reviewed. Data on CHC-related resource use were collected from diagnosis date to the end of 2007 or the last follow-up date or death date, depending on which date came first. Using micro-costing method, resource utilization categorized as laboratory tests, outpatient visits (OPD), inpatient admissions (IPD), procedures and medications were measured for 6 health states of CHC, i.e. CHC, compensated cirrhosis (CC), decompensated cirrhosis (DC), hepatocellular carcinoma (HCC), liver transplantation at year 1 (LT1), and subsequent years post-transplantation (LT2+). Costs were estimated using reference prices published by Ministry of Public Health and were valued in year 2008 Thai Baht (35 Baht = 1 USD). RESULTS: A total of 542 patients were identified with 1578 person-years of follow-up time. OPD rate was highest in HCC (7 visits/patient/year). IPD rates increased by 289% from CC to DC and 1377% from CC to HCC. Mean lengths of stay per admission were 9 days in DC and 6 days in HCC. Usage rates of medications for liver complications were also increased in DC and HCC. Average annual treatment costs per patient were: CHC 243,292 Baht (US$6,951); CC 251,148 Baht (US$7,176); DC 154,686 Baht (US$4,420); HCC 171,975 Baht (US$4,914); LT-1, 608,771 Baht (US$17,393) and LT2+ 100,818 Baht (US$2,881). CONCLUSIONS: Resource utilization rates in CHC patients increase as the disease progresses. Although inpatient bed charges are relatively low and no doctor fee paid for outpatient visits in public hospitals, consumption of these health care resources could have been avoided. Interventions which prevent or delay liver disease progressions will profoundly reduce economic burden of CHC.