As a complement of the study of the epidemiology of the arboviruses in Central Africa a survey of tick borne viruses has been done, in the Central African Republic, from December 1972 to June 1974; 15.103 ticks were collected, mainly from cattle at the slaughterhouses. They include: 10.085 Ambylomma variegatum, 4.113 Boophilus, 542 Rhipicephalus and 363 Hyalomma. From 892 monospecific pools inoculated into baby mice, 98 isolates of virus were obtained. Among the 57 isolates which have been fully identified (the identification of 41 other isolates is still in progress), 4 different serotypes of arbovirus have been found: Dugbe virus has been the most frequently found with 45 isolates from A. variegatum and I from B. decoloratus; this virus, previously isolated from human cases in Central African Republic in 1967 and 1970 has been isolated from a new human case in 1973. One isolate of CHF/Congo virus has been obtained from Hyalomma nitidum, but this virus has not yet been isolated from human beeings in C.A.R. The two other tick borne viruses isolated during this survey are Jos virus (9 isolates) and Bhanja virus (I isolate), all of them from A variegatum.