In the last few years the interest in the behavior and possible function of trace elements in biological systems has strongly increased. This seems to be stimulated by three different factors: i. e. 1. the slowly growing notion about the importance of some essential elements in the metabolism of plants and animals, including man, 2. the increasing extent of environ­ mental contamination caused by the disposal of heavy elements - both essential and toxic - and 3. the increasing sensitivity achieved in the analysis of these elements by modern techniques. The impact of the last mentioned development has been strong. Enormous improvements have indeed been made in lowering the limits of sensitivity of analytical methods maintaining at the same time good precision. Though there is a strong competition between some techniques, neutron activation analysis shows special advantages for multi-element analyses in organic materials. As a result a relatively important part of the literature on trace element behavior in the biosphere, though often phenomenologic in character, can be found in journals and transactions of symposia involving radiochemistry. This phenomenon does not readily stimulate the communication and scientific exchange with nutritional, toxicological, medical or biochemical experts who study the metabolic pathways of trace elements.