The study consists of three parallel investigations: (1) survey and critical review of the world-wide literature dealing with the ixodid ticks of Central Africa in general and of the Congo, Rwanda and Burundi in particular; (2) examination and identification of available ixodid tick materials previously collected in Central Africa (Congo, Rwanda and Burundi), comprising some 70,000 specimens; and (3) collection and identification of new materials coupled with field and laboratory observations on the biology and ecology of some of the tick species occurring in the Kivu Province of the Congo and in the Republic of Rwanda. Up to the present time, 78 species of ixodid ticks belonging to nine genera have been reported from Central Africa (Congo, Rwanda and Burundi). Of this, the presence of 75 species in this area is validated by available materials and new collections. The geographical distribution, as well as the list of affected hosts vary with each species. Most of these species occur on a variety of domestic and wild animals and are capable of causing severe economic losses to the livestock industry as well as transmitting agents of human diseases. The results of these studies are presented in such a way that each genus is treated as a discrete unit in which each species is dealt with from the viewpoint of taxonomy, distribution and hosts, biology, relationship to disease, diagnosis, description and illustration. The distribution of each of the species in the Congo, Rwanda and Burundi is plotted individually on maps, and keys to the identification of the adults of each species are presented in the treatment of each genus. (Author).