The HIV epidemic has been consistently associated with injection drug use and crack cocaine, but alcohol problems in HIV-infected persons are less well described. Our objectives were 2-fold: (1) to assess the prevalence of alcohol problems in HIV-infected patients initiating medical care; and (2) to determine the positive predictive value of the CAGE questionnaire for alcohol abuse or dependence in HIV-infected patients. Between July 1997 and October 2000, we assessed a consecutive series of patients who were establishing primary care for HIV infection (clinic sample), using an established alcohol screening test, the CAGE questionnaire. In addition, we enrolled other HIV-infected patients, including some of the clinic sample, who had two or more positive responses to the CAGE questionnaire into a longitudinal cohort (cohort sample), performed a diagnostic interview for lifetime history of alcohol abuse and dependence, and determined the positive predictive value of CAGE for alcohol diagnoses. In the clinic sample (n = 664), 42% (276 of 664) had two or more positive responses to the four CAGE questions. In the cohort sample (n = 141), 95% (134 of 141) met DSM-IV criteria for diagnosis of lifetime alcohol abuse or dependence. For patients initiating HIV primary care, a history of alcohol problems is very common. The CAGE questionnaire identifies a lifetime history of alcohol abuse or dependence in HIV-infected patients. Routine screening for alcohol problems should be performed in all patients entering HIV medical care and the CAGE questions are useful in this setting.