A method for the determination of rare earth elements, Y and Th in raw materials with different matrices is described. The sample is fused with Li2B4O7 and Cr and Mo are added as internal standards. Single elements can be determined in a wide range of concentrations, viz. Ce, Nd, La and Pr from 0.02 to 25% and Sm, Gd, Y, Th and Eu from 0.005 to 1%. The use of the LiF (110) crystal and, possibly, chemical separation, reduces the coincidence of lines to a minimum. Mutual interaction between single elements is prevented by the application of empirical corrections.