It has been shown that the replication of human immunodeficiency virus (HIV) can be suppressed in the clinical setting by drugs based on the selective in vitro antiretroviral activity. We now know that such antiretroviral chemotherapy can confer prolonged survival and improved quality of life in patients with advanced HIV infection. Hepatitis B virus (HBV) resembles retroviruses, including HIV, in several respects. In particular, both viruses contain reverse transcriptase and replicate through an RNA intermediate. Thus, emerging knowledge of the replicative cycle of HIV may provide a perspective for antiviral therapy of diseases caused by HBV.