The pupil cycle time (PCT) was estimated in 384 leprosy patients whose eyes looked normal on clinical examination and in an equal number of healthy controls. A statistically significant increase in PCT (p < 0.05) was noticed in leprosy patients, and corroborates the view that the ocular autonomic system may be affected without any visible clinical pathology in the eye. The clinical value and application of this finding is uncertain since the difference is only a few milliseconds. Young females with leprosy showed a conspicuous lengthening of PCT for which no plausible explanation is offered. There was a general trend for the PCT to increase as the spectrum of disease moved toward the lepromatous pole and a significantly higher PCT (p < 0.01) was found among multibacillary patients compared to paucibacillary patients. Patients who had had erythema nodosum leprosum (ENL) reactions showed a higher PCT than did those who had not had ENL. Patients who had had reversal reactions showed a decrease in PCT, which may be a statistical oddity in this hospital-based study. Patients whose duration of the disease was over 10 years showed a higher PCT, while smear positivity of a patient did not alter the PCT significantly.