Abstract: A method for the simultaneous determination of 8 rare earth elements inultrabasic rocks by neutron-activation analysis is described. Lanthanum, cerium,neodymium, samarium, europium, terbium, ytterbium and lutetium in eightsamples of periodate and harzburgite are analyzed. The rock samples are alltreated by chemical pre-treatment or radiochemical after-treatment in order toremove impurity elements and to enrich rare earth elements. This method ischecked and its reliability proved using Chinese geology standard samples DZ∑-1,DZ∑-2, GSD-7 and international standard sample BCR-1. The method is suitablefor ultrabasic rocks of 0.1 ng to 1 μg of rare earth elements per gram sample.