The Boron '97 meeting was a great success in summarising all recent developments in basic and applied research on boron's function, especially in plants. New techniques have since been developed and new insight has been gained into the role of boron in plant and animal metabolism. Nevertheless, there were still lots of open questions. The aim of the present workshop held in Bonn as a satellite meeting to the International Plant Nutrition Colloquium was thus to gather all actual information which has been gained since the Boron '97 meeting and to compile knowledge, both from animal and plant sciences. Furthermore, applied aspects had to be addressed too, as there is an increasing awareness of boron deficiencies even in crops such as wheat, which have formerly not been considered as responsive to boron application. Genetic differences in boron demand and efficiency within one species are a further important topic which has gained importance since the 1997 meeting. More in-depth knowledge on the mechanisms of boron efficiency are required as an increased efficiency will be one major possibility to maintain and improve crop yields for resource-poor farmers. Nevertheless, it has also clearly been shown that an adequate supply of boron is needed to obtain high yields of crops with a high quality, and that a sustainable agriculture has to provide an adequate boron supply to compensate for inevitable losses through leaching (especially in the humid tropics and temperate regions) and for the boron removal by the crop.