In tertiary mugmatites from the south of GDR the contents of Na, Fe and 20 trace elements are determined by INAA. For 9 phonolithes and other basaltic rocks mean values and concentration intervals uf the elements determined are represented. Comparison of some results determined parallel with optical analytical methods give average deviations for Fe and Na of approximately 3% and for Ba, Cr and Ni of about 20%. The results of U- and Th-determination are compared by measurements of natural radioactivity. Average deviations run to 10%. The use of Cr, Sc and Th as indicator elements of magmalic differentiation is discussed.