Remarks The present report was prepared to update the former report on naturally occurring radionuclides in human tissues (A/AC 82/G/L.1045) with the addition of newly acquired information and to include some old data which was taken from the 1962 UNSCEAR report for the purpose of comparison. However, only limited data was included here from these old publications because of the following reasons. Some data is concerned with only total alpha activity. Other with nuclide content in whole body ashe And,some data on nuclide content in bone ash is included again in more recent reports by the same authors. The information in high natural radiation areas is still scanty because of the difficulty of sampling human tissues in such areas. Several old figures on Ra226 in the bones of inhabitants in Kerala, India, showed a much higher value than in normal bones. But there is little data available. (table 1) The recent data on samples of teeth collected in the Arax4 and Tapira region of Brazil, where high radioactive intrusives are found, revealed a tondency toward a higher content of Ra226 than in other regions. (table 1) Further, the teeth of two Indian tribos in Brazil that eat Byggil nuts, were found to show a several times higher content of Ra than in those of the inhabitants of New Jersey which were analyzed at the samc time. (table 2) Pp210 jevels in bones of Canadian Eskimos who had beon permanent residents in the Arctic were found to be considerably higher than the levels in bones of Canadian Eskimos who had been residing in southern Canada for some time prior to removal of the bone. (table 4) This high value is probably due to the special food=chain of lichen— reindecer~Eskimose The same phenomenon was also found for soft tissues as the result of high P0210 content in placenta of Canadian Arctic Eskimos. (table 7) Attention B38 been paid recently to the cffect of cigarette smoking on the Po content in human tissues. It was found through research on various parts of lung tissuoc of smokers that there is a considerably higher level of Po?l0 content than in those of non- smokers. (table 7)