OBJECTIVES: to estimate the C/E of lamivudine in the treatment of chronic hepatitis B (CHB) in Poland. METHODS: Model for the Polish health-care context was developed, based on the use of clinical data from literature and local data on health-care resource utilisation and unit cost. Costs and effects of a population of CHB patients were modelled using 4 scenarios, which attempt to reflect real-life practice, in which patients may receive any of the treatment options available and a proportion of patients may still receive no treatment because therapy is not suitable. Scenario A and B assumed the availability of both treatment options: the first choice of treatment is in A- lamivudine and in B - INFa. In scenario C the only approved treatment is INFa, in scenario D patient receive no antiviral treatment. The measure of outcomes were: HBeAg seroconversion and nonprogression to cirrhosis. Only direct medical costs were analysed. The perspective of health-care payers and time horizon of 1 year were taken. The one-way sensitivity analysis and extreme scenario analysis were performed. RESULTS: The best results in terms of seroconversion and nonprogression to cirrhosis were achieved in scenario A, costs were lowest in scenario D. Mean cost/HBeAg seroconvertion and mean cost/cirrhosis avoided were (in PLN, 1 USD=4 PLN): for A – 35238 and 6480, for B – 72654 and 16289, for C – 49370 and 8689, for D – 20985 and 1474. The incremental analysis vs scenario D indicated, that A is more costs-effective alternative than B and C. Changing in value of key drivers for sensitivity analysis did not have any significant effect on the ICER. CONCLUSIONS: Lamivudine as the first choice treatment of CHB (scenario A) allows to receive the best results in terms of seroconversion and nonprogression to cirrhosis. This is the most cost-effective alternative to “no treatment” (scenario D).