I speak from the perspective of the director of a major botanic garden ( Fig. 1a) with a programme of research on plant and microbial biodiversity, world-wide, and as a plant pathologist. What I say is not intended as a comprehensive review of an academic subject. My aim, quite simply, is to place on the agenda of the 7th International Congress of Plant Pathology the subjects of biodiversity and conservation, and to suggest that the British Society for Plant Pathology and the International Society for Plant Pathology urgently consider the formulation of conservation policies for plants and their pathogens. First I shall consider the threats to plant diversity. Next I shall discuss the importance of conserving that diversity and will assess progress to date. This will lead on to the controversial subject of the conservation of plant pathogen diversity, both ex situ and in situ. Finally, I shall stress the importance of education to the conservation effort.