Abstract: The invention provides a method of preparation of HBV genomic amplicons which makes it possible, using the same amplicon obtained from a patient, to evaluate HBV strains resistant to antiviral agents by analysing, their genotype, their phenotype and their replicative capacity. The method of the invention guarantees to obtain the closest in vitro replication capability compared to the in vivo replication and ensures that the influences of all the mutations present on a viral genome are taken into account when evaluating the drug sensitivity and the replicative capacity.