Clinic patients and students were given several regular drops of commercial 10% phenylephrine HCl, and 1.0% cyclopentolate HCl or 1.0% tropicamide HCl. The drops were given three times at five-minute intervals. Mydriasis and cycloplegia were determined and compared with the results obtained by using one of the following: microdrops (0.005 or 0.01 ml) of a mixture of 5% phenylephrine HCl and 0.5% tropicamide HCl, or regular drops of mixtures of 1% phenylephrine HCl, or 0.4% hydroxyamphetamine hydrobromide with 0.1% cyclopentolate HCl, or 0.1% tropicamide in a vehicle of 1.6% or 1.0% methylcellulose 400, or artificial tears or lubricants (Absorbobase, Contique, Isopto Tears, Liquifilm, Lyteers, Ultra Tears). Except for an initial lag in the production of mydriasis with the diluted mixtures, the results were similar for all preparations. The diluted solutions produced little ocular irritation or tearing.