Genetic variation in crop species and their wild relatives holds the key to the successful breeding of improved crop cultivars with durable resistance to disease . The importance of the conservation, characterization and utilization of plant genetic resources nationally and internationally has been recognised, though much remains to be done . Gene banks have now been established in many countries and at most of the international crop research centres . Cell and tissue culture techniques and biotechnological aids have done much to ensure the creation and safe transfer of healthy germplasm around the world . Multidisciplinary, international research and collaboration are essential to the successful breeding of improved disease resistant cultivars . Examples are given of the effective use of genetic resources in breeding disease resistant cultivars of a number of crops, including cotton, rice, potatoes and pearl millet .