This paper presents a review of pertinent literature related to studies of self-sterility in the genus Coffea and reports the results of cytological and genetic studies carried out on the species C. canephora at the Instituto Agronômico, Campinas, Brasil. The objetive of the study was to determine the degree and causes of self-sterility in the species C. canephora. In tests involving a large number of self-pollinations in flowers of this species, all were self-sterile and formed, no seed. In tests of cross-pollinations involving C. canephora approximately 50 percent were effective in the formation of seed. Cytological studies showed that the formation of the embryo-sac and pollen grains in C. canephora can be considered normal. Likewise a study of the pollen of this species on artificial media under controlled conditions, showed 55 percent germination and this was considered sufficient to bring about fertilization. In contrast, the cytological investigations of self-pollinated flowers showed that the number of pollen grains that germinated was very small and of those that did germinate, the formed pollen-tube was short and did not extend beyond the stigmatic papillae. Observations on compatible cross-pollinations on C. canephora showed that a large number of pollen grains germinated and that usually there were several pollen-tubes within the style. However, the rate of growth of pollen-tubes in C. canephora was found to be much slower that in C. arabica. The present investigation has shown that in flowers of C. canephora there is a very high degree of self-sterility and this has been related to poor germination of the pollen grains and subsequent limitation in the development of pollen tubes.