Supersensitivity of the iris sphincter to dilute parasympathetic or sympathetic agents in a preganglionic oculomotor nerve disorder is considered a diagnostic test of a brain death. We studied pupillary response to 0.06% pilocarpine and 1.25% phenylephrine in cases of brain death confirmed with EEG9(19 cases) and clinical brain death not confirmed with EEG(10 cases). 0.06% pilocarpine was instilled if the diameter of the pupil was over 4.0 mm, 1.25% phenylephrine under 4.0 mm. Among 8 cases of clinical brain death associated with dilated pupil, four cases showed positive response to 0.06% pilocarpine. Not only two cases of them who showed flat EEG considered the brain death(50%) but the other two cases who showed lower voltage in EEG also were dead in 36 hours after the test. Two cases associated with constricted pupils who showed positive response to 1.25% phenylephrine, but only lower voltage in EEG, were consequently dead in 48 hours. Nineteen brain death patents confirmed with flat EEG showed strong positive response to these drugs. Our results suggest that the dilated pupil is not necessarily considered as a diagnostic hallmark of the brain death which has been established by Korean Medical Association, and it seems that pupillary responses to the autonomic stimulating agents appears more reliable than vestibuloocular reflex test.