OBJECTIVES: To estimate the impact of tenofovir reimbursement in treatment of adults with chronic hepatitis B in Poland. METHODS: Analysis was performed from the public payer perspective in 5-year time horizon. Target population was defined as adults with chronic hepatitis B who are eligible for antiviral treatment. Size of the target population was estimated on the basis of Polish sales data obtained from IMS, including the sale of nucleoside analogues in the period January 2007-March 2010. In the analysis following cost categories were included: drugs (tenofovir, entecavir, adefovir, lamivudine), monitoring, hospitalizations and complications of hepatitis-B (cirrhosis, hepatocellular carcinoma). Reimbursement assumption was that tenofovir will be financed in heath therapeutic program on the basis of financing principles of entecavir and adefovir. It was assumed that tenofovir will be initial (first choice) therapy in population of patients who are eligible to tenofovir, entecavir or adefovir therapy and that in case of reimbursement tenofovir will be replacing entecavir and adefovir. RESULTS: The size of target population will be circa 4100 people in 2011 and increases to circa 6200 people in 2015. Forecast population of patients using tenofovir is ca 1500 patients in 2011 and will grow to ca 3200 patients in 2015. In current scenario (lack of tenofovir reimbursement) expenditures on antiviral drugs in target population will be ca 76,000,000 PLN in 2011 and will steadily increase to ca 120,000,000 PLN in 2015. Total expenditures in the target population would be ca 130,000,000 PLN in 2011 and will steadily increase to ca 202,000,000 PLN in 2015. In case of tenofovir reimbursement estimated decrease in total expenditures will be ca 6,000,000 PLN in 2011 and ca 11,000,000 PLN in 2015. CONCLUSIONS: The decision for tenofovir reimbursement will cause decrease in public payer expenditures for patients with chronic hepatitis B.