This paper gives an overview of biodiversity and how it is impacted by agricultural biotechnology, building upon chapters on the impact of biotechnology on biodiversity for the European Federation of Biotechnology (Braun & Bennett, 2001) and UNESCO (Braun & Ammann, 2002). Biodiversity encompasses the fundamental bases of life on earth, including genetic, species and ecosystem diversity. There is a need to better understand biodiversity in terms of its fundamental components (genes and taxa), the interrelatedness of these components (ecology), their importance for human life and life in general, and the factors that threaten biodiversity. Within the tropics, Biodiversity is still concentrated in unmanaged habitats. In temperate zones, particularly in the European Union, almost 50% of the landscape is agricultural, and agricultural lands contain a significant portion of the biodiversity in these zones. The greatest threats to biodiversity are destruction and deterioration of habitats, particularly in tropical developing countries, and introductions of exotic species. Maintaining biodiversity requires addressing these threats.