Chronic hepatitis B affects nearly 10% of HIV-infected patients. Thus, approximately four million people worldwide are HBV/HIV coinfected. Hepatitis B virus (HBV) infection is a dynamic disease and coinfection with HIV impacts directly on the outcome of HBV infection, considerably complicating its natural history, diagnosis, and management. Hepatic necroinflammation is lower in HBV/HIV coinfection, yet liver damage, especially fibrosis, progresses at a faster rate than in HBV monoinfection. With improved control of HIV disease with HAART, liver disease has emerged as one of the leading causes of death in patients with HIV Anti-HBV therapy should be considered for all HIV/HBV-coinfected patients with evidence of liver disease, irrespective of the CD4 cell count. In coinfected patients not requiring HAART, HBV therapy should be based on agents with no HIV activity such as adefovir. In contrast, in patients with CD4 counts less than 350 cells/microl, the use of agents with dual anti-HIV and anti-HBV activity should be considered. Combination therapy should ideally be used to avoid or delay the development of antiviral resistance. Regular monitoring of patients is imperative to recognize reactivation and subsequent need for treatment, and to identify drug resistance and viral breakthrough early. Similar close monitoring is required for patients presenting with advanced HIV infection and reduced functional hepatic reserve due to HBV-related cirrhosis. Effective antiviral treatment can precipitate immune reconstitution disease resulting in serious hepatic flare and precipitating liver decompensation. Clearly, more data are needed to more effectively treat HIV/HBV coinfection.