The uranium microdistribution by the fission track method and mean uranium content by the delayed neutron method in more than 20 taxa from Greek localities is studied. The included materials come from 27 localities which stratigraphically cover the time span from Miocene to Holocene. Whenever it was possible, enamel, dentine, cement, mandibular bone, and surrounding or enclosed sediment were analyzed separately. Obtained values varied from 1778 ppm to less than 1 ppm, while uranium content is not the same in enamel, dentine, and cement of one single tooth. It becomes evident that parameters affecting uranium concentration and its microdistribution are numerous and constantly changing with geological time in relation to palaeoenvironmental factors.