However, cases of Lamivudine resistance have been reported and the rate of Lamivudine resistance has been increased after long-term therapy. Objectives: Detect rtL180M and rtM204V / I Lamivudine-resistant mutants by Real-time PCR Methods: 50 serum samples were collected from chronic HBV infected patients who have been receiving an antiviral therapy with Lamivudine. Real-time PCR assay and sequencing were performed on these samples to detect rtL180M and rtM204V / I mutants. Results: There were 11/50 samples with rt180M mutations, 9/50 samples with rt204V mutations and 12/50 samples with rt204I mutations.