Coffee trees belong to the botanical genus Coffea in the family Rubiaceae. In this chapter, the genetic resources of Coflea will be considered. Considerations of its botany have been detailed elsewhere.' Here we are more interested in the specificity of genetic resource studies and their utilisation in coffee breeding. Current commercial green coffee production relies on only two species, C. arabica and C. canephora, which are described in detail in Chapters 2 and 3. But, in fact, coffee beans can be produced by many other species of Coffea. Therefore we do not present data just for these two species; we emphasise the value of all the species. The gene pool useful for C. arabica and C. canephora breeding is made up of all Coffea species, as will be demonstrated later. In this chapter, we review our present knowledge about wild coffee species. This knowledge has been acquired from studies of wild coffee populations in the forest as well as from experimental hybridisation tests. New genetic analysis methods have been applied to coffee material. A short description of these methods is given in section 2, and may be useful