The intraocular pressure response to topically instilled 0.25% betaxolol hydrochloride was evaluated in 12 patients with chronic open angle glaucoma or ocular hypertension. The drug produced a significant lowering of IOP in all 12 of the patients under study. A 30% to 35% decrease below baseline IOP was observed and was maintained during the one-year observation period. Visual acuity was stable in all subjects throughout the study and corneal anesthesia was not encountered. Tear secretion was not adversely effected by betaxolol, nor did topical administration of the drug produce any systemic cardiovascular response of consequence. Blood pressure and pulse rate remained stable throughout the year. These data suggest that an ophthalmic formulation of betaxolol may have substantial clinical potential for the treatment of glaucoma.