In 37 patients with alcoholic liver disease urinary alcohol was measured daily for up to 6 months. Every week the patients were asked about their drinking during the past week. Those who convinced the physicians of their abstinence were recorded as not drinking. Patients with alcohol in their urines convincingly denied alcohol intake 52% of the times that they were questioned. 25% of them denied drinking every time. Only 17% of all patients admitted it at all times. Patients who always admitted to drinking had an average urinary alcohol value of 1420 +/- 66 mg/l, compared to 81 +/- 5 mg/l in those who denied drinking every time. Those who admitted drinking intermittently had significantly higher urinary alcohol values (1001 +/- 57 mg/l) when admitting than when denying (538 +/- mg/l). The personal interview should not be used to separate populations of abstainers and non-abstainers in the follow-up of alcoholic patients. On the other hand, deniers appear to consume less alcohol than those who admit their drinking.