Both long term follow up and real world research on chronic hepatitis B have accumulated data on nucleos (t) ide analogues in anti-HBV treatment,which shows that resistance mutation turns out to be the major obstacle in achieving response.Identification of genotypic resistance at early stage is key to improve strategy.Deep-sequencing will be helpful to predict resistance earlier.Direct acting autiviral agents on hepatitic C virus tell us resistance at the very beginning,however,more data is still needed to elucidate how to use resistance monitoring of anti-HCV treatment.