Breath alcohol devices are routinely employed by emergency department personnel to reflect blood ethanol levels. No data have been published using these devices following the ingestion of "alcohol-free" beer that are required to contain < 0.5% alcohol. We performed a prospective, randomized, unblinded study on 8 healthy male volunteers that abstained from alcohol for 48 h and fasted for 10 h. Each subject ingested a 6-pack of alcohol-free beer over 1 h; breath alcohol determinations were made at 30, 60 and 120 min. Elevated breath alcohol levels were obtained at 30 and 60 min and decreased in all but 1 subject by 120 min. The elevated breath alcohol levels at 30 and 60 min may represent the previously reported "mouthwash" effect.