The study's aim was to identify the prevalence of alcohol problems among methadone maintenance patients and to consider resource implications in assessing and monitoring these problems. Alcohol consumption was measured primarily by self-reports obtained through structured interviews. Levels of consumption were determined by two methods: the number of days of consumption in the last 30 days and the typical amount consumed each day; and a retrospective recall, 7-day "drink diary" in which the types of beverage and number of units consumed on each occasion were recorded. Subjects were also administered the Severity of Alcohol Dependence Questionnaire, which is designed to measure physical and affective symptoms of alcohol withdrawal and craving, typical daily alcohol consumption, and symptoms of heavy drinking within the last 6 months. A breathalyzer was used to measure the level of alcohol in the blood at the time of an interview. Liver function tests were used to determine any recent excessive use of alcohol. The study found that although 42 percent of the subjects had been abstinent from alcohol use for the previous month, mean alcohol consumption among drinkers was 33.5 units of alcohol in the last week, with 25 patients (23 percent) drinking at levels that may be regarded as dangerous (more than 50 standard units of alcohol per week). Positive correlations were found between self-reported measures of alcohol use, severity of alcohol dependence, and breathalyzer scores. Associations between self-report alcohol measures and physiological indexes of liver dysfunction were positive but weak. A minority of methadone maintenance patients apparently had an alcohol problem that constituted a significant additional challenge to their health and well-being. 3 tables and 19 references