Background: Third generation beta blockers have an intrinsic simpatico-mimetic activity and are cardioselective. Therefore, they should not have adverse bronchial effects and could even have a slight bronchodilator activity. Aim: To test the efficacy and safety of celiprolol in hypertensive patients with chronic obstructive lung disease. Patients and methods: Uncomplicated hypertensive patients with chronic obstructive lung disease received celiprolol during 12 weeks. They were subjected to monthly clinical assessment and ventilatory function was measured on the basal period and at the end of the trial. Results: During the study period, blood pressure fell significantly from 179±6/112±8 to 161±4,7/98±1.6 mmHg. No changes were observed in forced expiratory volume in 1 s or in forced expiratory flow between 25 and 75% of the vital capacity. No subjective changes in respiratory function were reported during the trial. Conclusions: No changes in ventilatory function were observed in these patients with chronic obstructive lung disease, treated with celiprolol during 12 weeks. (Rev Méd Chile 2000; 128: 59-63)