Abstract: Total number of 807 tissue blocks of various peripheral,nerve trunk's taken from 70 autopsied cases of lepromatous leprosy has been studied.It was found that the incidence rate of lesion in various nerve trunks was quite different,with the highest incideuce rate of lesion in ulnar nerve (98.2%),common fibular nerve (97.8%).and median nerve(90:2%).314 Pairs of bilateral tissue blocks taken from the same level of the same nerve have been examined,and the result showed that the ratio of unilateral nerve lesion to bilateral nerve lesion was generally 1:5.It means,that the lesions in nerve trunks of lepromatous leprosy were not generalized,symmetrically distributed,at least not diffusely affecting the entire length of the nerve.From the difference in cellular infiltrates of a given nerve,we can divide the lesions of nerve trunks into progressive stage,regressive stage,and quiescent stage.Correlating nerve trunk lesions to skin lesions in 57 cases studied,we found that the process of regression in skin lesion was faster than that in peripheral nerve trunk.