1 The airway response to inhaled prostaglandin E2 (PGE2) and the effect of oral propranolol on this response was studied in eight normal subjects in a double-blind randomised trial. The airway response was measured as specific airway conductance (sGaw). 2 Inhalation of PGE2 caused retrosternal soreness, coughing and an awareness of mucus production. Despite this, PGE2 caused bronchodilatation and reproducible dose-response curves were obtained, with a maximum increase in sGaw of 53%. 3 Inhalation of the diluent of PGE2, an ethanol/saline mixture, did not cause irritation nor did it alter sGaw. 4 Prior administration of propranolol 80 mg did not alter baseline sGAW, nor the response to PGE2, indicating that the action of PGE2 in vivo is unaffected by bronchial beta-adrenoceptor blockade. 5 This technique should be of value in studying bronchodilator prostaglandins and their interaction with other drugs.