We describe a patient who accidentally received an infusion of cyclosporin at a rate of 30 mg/hr during 13 hr instead of the prescribed dose of 3 mg/hr and who concomitantly developed massive intracerebral edema with brainstem compression and death. A cyclosporin level as high as 1700 ng/ml could have been reached before the drug was withdrawn. To the best of our knowledge, this is the first case of fatal cyclosporin overdose reported in an adult patient.