S-32-468, a recently synthesized aryloxymethyl beta-adrenoceptor antagonist, was tested for its ability to inhibit activation of isoproterenol-stimulated adenylate cyclase activity in rabbit and human ciliary process, heart and lung. In both species, S-32-468 was a potent inhibitor of ocular beta-adrenoceptors, with a 9-12 fold selectivity over inhibition of beta-adrenoceptors in cardiac tissue. When applied topically, S-32-468 was more effective than timolol in decreasing intraocular pressure in normal albino rabbits.