Celiprolol, a new beta-adrenoceptor antagonist, blocks serotonin- and methacholine-mediated bronchoconstriction in animals, even in the presence of propranolol. In two, randomized, placebo-controlled, 5-way crossover trials, the pulmonary effects of celiprolol 200 and 400 mg, propranolol 40 mg and atenolol 100 mg were compared in 34 asthmatic patients. Pulmonary function was measured after single doses of each agent, and again following subsequent, graded doses of albuterol or isoproterenol aerosol. Changes in one-second forced expiratory volume (FEV1) and maximal midexpiratory flow rate (FEF25-75) prior to albuterol or isoproterenol were positive after placebo and both doses of celiprolol. Propranolol, and to a lesser extent, atenolol, caused significant reductions in both measures of pulmonary function. Overall changes in FEV1 following each drug plus isoproterenol or albuterol were positive, in the rank order, celiprolol approximately placebo greater than atenolol greater than propranolol. Propranolol pretreatment caused a significant reduction in the effect of bronchodilator. Unlike atenolol and propranolol, celiprolol was highly bronchosparing and did not antagonize sympathomimetic bronchodilators.