Pupil cycle time was measured in fellow eyes of 118 patients with closed-angle glaucoma and 70 age- and sex-matched control subjects. Results indicate that the duration of pupil cycle time was significantly prolonged in patients with closed-angle glaucoma as compared to the control group (p less than 0.001); in addition, the prevalence of absent pupillary oscillation was significantly increased in closed-angle glaucoma patients (p less than 0.001). The implications are discussed, with particular reference to the association between closed-angle glaucoma and systemic parasympathetic neuropathy.