During 1984 and 1985, six Rift Valley Fever virus strains (RVF) were isolated in Central African Republic, among them five from human samples. Three strains were isolated in 1985 at the end of the rainy season, from sera of patients dead with severe jaundice with haemorrhagic syndrome, what could evoke a little outbreak. At this occasion, these RVF strains and the other strains of phleboviruses previously isolated in CAR, were antigenically compared by Immuno-fluorescent assay (IFA) and Complement Fixation Test (CF), using mice immuno ascitic fluids prepared against each strain. A lot of cross reactions were noted between the different strains, but all the RVF strains seem to have the same antigenic outline.