Th(NO(3))(4).5H(2)O reacts with H(2)pyr(2)pen {propylenediamine-bis(pyridoxylideneimine)}, UO(2)(NO(3))(2).6H(2)O reacts with H(2)pyr(2)pen and H(2)pyr(2)dien {diethylenetriamine-bis(pyridoxylideneimine)} under deprotonation of the endo hydroxyl groups of the Schiff bases rings to give the chelate complexes [Th(pyr(2)pen)(2)] (1), [UO(2)(pyr(2)pen)(CH(3)OH)] (2) and [UO(2)(pyr(2)dien)].2H(2)O (3). In 1 the thorium center is the common vertex of two square pyramids displaced on 45 degrees to each other. In 2 and 3 the uranium atoms are the centers of distorted pentagonal bipyramides. In 2 a methanol molecule achieves the coordination number 7 of the uranium(VI) ion, in 3 the central N atom of the dien section of the ligand accomplishes the coordination polyhedra, resulting a chelate complex with remarkable higher symmetry. Some radiological factors are also discussed, correlating the knowledges of new chemical properties of uranium and thorium with the understanding of its metabolism in living beings, what, in principle, should give support for clinical studies about prevention, diagnosis and treatment of uranium, thorium and/or heavy metals poisoning.