The accommodative effects of α- and β-adrenergic stimulation were investigated in human subjects by measuring changes in the response ACA ratio and in the response accommodative amplitude as a result of instilling hydroxyamphetamine hydrobromide and phenylephrine hydrochloride. Statistically significant increases in the ACA ratios were found to result from hydroxyamphetamine hydrobromide, but not from phenylephrine hydrochloride. The accommodative amplitude significantly decreased under the influence of each agent. It was concluded that these adrenergic effects on accommodation were mediated through the β-receptor sites. This provides further evidence of the dual autonomic innervation of accommodation.