The effects of the d- and 1-isomers of epinephrine and norepinephrine have been determined on intraocular pressure (IOP) in conscious rabbits and rhesus monkeys, and on aqueous humor turnover rate (AHTR) in rabbits. Relatively specific beta-adrenergic antagonists (butoxamine and metoprolol) were used to attempt to modify the responses. The effects on IOP in both species are similar to those of racemic mixtures. The d- and 1-isomers of norepinephrine and epinephrine reduced IOP, and reduced AHTR in rabbits. The d- and 1-isomers of norepinephrine had little effect on IOP in monkeys while d- and 1-epinephrine increased IOP. Metoprolol, a beta 1-antagonist was more effective than butoxamine (beta 2-antagonist) at modifying the effect of the norepinephrine isomers in rabbits.