OBJECTIVES: Despite a significant decrease over the last 20 years, the prevalence of hepatitis B remains high in Portugal (an estimated 36,000 cases in 2002). Hepatitis B represents a relevant public health issue due to its dramatic consequences when it turns chronic, namely the associated risk of cirrhosis and hepatocellular carcinoma. The aim of this study was to estimate annual cost of disease states associated with chronic hepatitis B (CHB) from the perspective of Portuguese NHS. METHODS: We estimated the resource use to treat CHB and its disease states, namely Compensated Cirrhosis (CC), Decompensated Cirrhosis (DC), Hepatocellular Carcinoma (HCC) and Liver Transplantation follow-up (LT).A panel of 8 specialists from Portuguese NHS hospitals were surveyed using a modified Delphi technique. Data were collected for outpatient visits, laboratory tests, diagnostic and therapeutic procedures, drugs (excluding antivirals) and hospitalisations. RESULTS: The resource use for all categories increases with severity of disease. Estimated average annual costs are €1,125 for CHB, €1,761 for CC, €18,278 for DC and €26,388 for HCC. Cost for LT procedure within Portuguese DRG is estimated at €100,785, while average post-LT costs are estimated at €30,540 and €24,780 for the first and subsequent years, respectively. Costs for CHB and CC are mainly due to outpatient visits and serology tests. By contrast, inpatient days are the main driver of costs for DC (79%), HCC (50%) and post-LT in the first year after treatment (71%). Drugs represent the second major component of costs for HCC (18%), and post-LT in the first (23%) and second (72%) year, related to immunosuppressants and hepatitis B immunoglobulin respectively. CONCLUSIONS: Our study shows that annual costs of managing CHB disease states are high and increase substantially with disease severity. Both economic arguments and public health ones point to the necessity to control CHB infection and its progression.