We evaluated the use of topically administered betaxolol 0.5% in 101 glaucoma patients (47 men and 54 women) who had chronic obstructive pulmonary disease, asthma, or timolol-induced bronchoconstriction. Betaxolol 0.5% was administered twice daily and patients were reexamined at three-month intervals for up to two years. In addition to measurement of intraocular pressure, pulmonary function tests were obtained before therapy (baseline), two or three weeks after initiating betaxolol therapy, and at yearly intervals. Before treatment with betaxolol, the mean ratio of forced expiratory volumes in one second (FEV1) to forced vital capacity (FVC) was 66.3% (n = 101). After two weeks of betaxolol treatment, mean FEV1/FVC ratio was 66.2% (n = 101). After one year of betaxolol therapy, mean FEV1/FVC ratio was 60.1% (n = 24), and after two years it was 54.4% (n = 5). Nine patients developed symptoms that may have been associated with betaxolol treatment and were withdrawn from the study. Five of these patients developed symptomatic pulmonary obstruction between one and 554 days after initiating betaxolol treatment. Topically administered betaxolol was well tolerated by most glaucoma patients with concomitant pulmonary disease.