The horizontal diameter of the pupil was measured on 20 eyes with exfoliation syndrome and 20 control eyes before and after the instillation of 10% phenylephrine and 4% pilocarpine eye drops. Pupil dilation induced by topical application of the alpha 1 adrenoceptor agonist phenylephrine was significantly smaller in eyes with exfoliation syndrome compared to controls. The cholinergic agonist pilocarpine decreased pupil diameter and this effect was significantly less in cases with exfoliation syndrome. We conclude from these data that the pharmacological response to both adrenergic and cholinergic stimulation is weaker in eyes with exfoliation syndrome compared to controls.