The acute effect of ethanol inhalation on ventilatory capacity was studied in a group of six healthy volunteers and the results were compared to those obtained after the inhalation of a saline solution. There was a significant decrease in flow rates on partial expiratory flow-volume (PEFV) curves up to 90 min after ethanol inhalation. FEV1 values did not change significantly, either after ethanol or saline aerosol. Pretreatment with atropine did not prevent the acute reductions in flow rates in comparison with the reductions without atropine. Pretreatment with disodium cromoglycate (DSCG) considerably diminished the acute reductions of flow rates caused by ethanol inhalation. These results suggest that ethanol in some persons may act, at least partly, through releasing mediators with bronchoconstrictive action.