The Canterbury alcoholism screening test (CAST) was developed from data collected on 2014 consecutive non-paediatric general hospital admissions. The CAST correctly identified 95% of patients classified by the short MAST as definitely alcoholic, and misclassified only 1.6% of controls. When administered to 165 patients from various alcoholism treatment centres, the CAST classified all patients as having alcohol problems. The screening test consists of two parts adapted from the Munich alcoholism test (MALT): a twenty-three item self-report section and a four item clinician's assessment. The CAST, which takes about four minutes to administer, has considerable potential use for the early detection of patients with current alcohol problems in an unselected hospital population.