Tropicamide 0.5% was topically applied to the eyes of thirteen subjects to study its effectiveness as a mydriatic. A comparison was made between the subjects with light colored irides and those with dark brown irides, and also between those who had worn contact lenses previous to dilation and those who had not. Results indicate that a minimum pupil size of 6 mm was achieved within 25 minutes after instillation and this dilation was independent of iris pigmentation. Typically, IOP was reduced during dilation with tropicamide.