Between June 1994 and February 2003, a total of 111 human immunodeficiency virus (HIV)-infected patients with chronic hepatitis B virus (HBV) coinfection and 387 HIV-infected patients without HBV or hepatitis C virus coinfection were prospectively observed to assess the impact of HBV infection on outcomes of HIV-infected patients. After a median duration of observation of 25 months, coinfected patients were more likely to develop hepatitis (adjusted hazard ratio [AHR], 2.54; 95% confidence interval [CI], 1.69-3.82) and hepatic decompensation (adjusted odds ratio [AOR], 9.94; 95% CI, 1.89-52.35). Although similar proportions of the 2 patient groups had an increase in the CD4 count by > or =100x10(6) cells/L (AOR, 0.78; 95% CI, 0.45-1.36) and development of new opportunistic illnesses (AOR, 0.94; 95% CI, 0.53-1.66), HBV-infected patients had an increased risk for virologic failure (AOR, 1.76; 95% CI, 1.03-2.99) and death (AHR, 1.71; 95% CI, 1.19-2.47) after highly active antiretroviral therapy was initiated.