OBJECTIVE: Approximately 700,000 people in Spain are infected with HBV. The medical costs associated with chronic HBV have not yet been studied in Spain. This research aims to estimate the treatment patterns of major HBV health states and their associated costs. METHODS: Resource use patterns were determined by a panel of physicians caring for HBV patients in three hospitals using a questionnaire. A review of the literature on the cost of the disease was also carried out. Average values of health resource utilisation were computed for patients with chronic hepatitis B (CHB), compensated and decompensated cirrhosis (CC and DC), hepatocellular carcinoma (HC) and liver transplantation (LT). Unit costs were derived from the Soikos health unit costs database. RESULTS: No variations in clinical practice were detected among the experts consulted. The estimated annual cost is €3396 for CHB (€8493 if treated with antiviral therapy -33% patients- and €850 for patients without antivirals). Estimated annual cost for CC is €3997 (€7486 if treated with antiviral therapy -50% patients- and €510 for patients without antivirals). Average annual cost of DC (including ascites, bacterial peritonitis, variceal haemorrhage and hepatic encephalopathy) is €6851. Hepatocellular carcinoma costs €3,731 annually with few patients receiving chemotherapy. Liver transplantation was estimated to cost €25,165 for the transplantation phase and €5,770 in the first year post transplant. CONCLUSIONS: The results obtained, although not fully representative for Spain due to the small number of hospitals sampled, show that the costs associated with chronic HBV are significant. The most severe stages such as episodes of decompensated cirrhosis and transplantation are the major cost drivers. Adopting therapies that slow or stop disease progression could reduce morbidity and mortality and also the cost burden to the health care system.