Summary. Coinfection with hepatitis B virus (HBV) is an important and preventable cause of chronic liver disease among HIV-infected patients. We calculated the prevalence of chronic HBV infection annually from 1996 to 2007 by age, gender, race/ethnicity, and HIV transmission risk in a multisite observational cohort study of HIV-infected patients. Prevalence of chronic HBV infection was calculated as the number of patients with a positive HBsAg or detectable HBV DNA divided by the number of patients tested using either one of these assays. Among 4467 (59%) patients tested for chronic HBV infection from a total of 7618 patients active during 1996–2007, median age was 38.5 years, 77% were men, 49% were white, 35% were black, 13% were Hispanic, and 53% were men who had sex with men (MSM). Overall, 8.4% tested positive for HBsAg or detectable HBV DNA. Annual chronic HBV prevalence during 1996–2007 ranged from 7.8% to 8.6% without a statistically significant trend. Overall, prevalence was greater among men compared with women; among whites, blacks, and persons of other race compared with Hispanics; among MSM compared with injection drug users and high-risk heterosexuals; and among patients aged 35–44 years compared with younger or older patients. MSM constituted the greatest fraction (63–72%) of all HBV-infected patients in the HIV Outpatient Study (HOPS) over the period. Of eligible patients, 5.8%, 23.4%, and 31.6% had received at least one dose of HBV vaccine by years 1996, 2002, and 2007, respectively. Despite the availability of an effective HBV vaccine for over two decades and long-standing recommendations for immunization of persons (with or without HIV infection) at risk for HBV, the prevalence of chronic HBV infection in this study has been largely unchanged over the past decade among patients in all groups, and overall was 20 times as high as the national population prevalence.