The circulation of the rickettsiae R.africae and C.brunetii, the causative agents of African tick-bite spotted fever and Q fever, was first ascertained throughout the territory of the Republic of Guinea. The immune stratum against R.africae among the population varied 1.1 to 25.4% or 10.6+/-0.7% on average and that among the livestock did 0.6 to 18.8% or 7.6+/-0.6% on average. The proportion of sera to C,brunettii in the population was in the rage from 0.8 to 10.5% or 2.4+/-0.3% on average; that in livestock was 3.2 to 18.7% or 8.0+/-0.6% on average. However, many aspects of the circulation of rickettsiae, the pathology and importance of these fevers in the structure of morbidity in Guinea remain still unclarified and call for further investigations, by applying the current laboratory diagnostic tests for rickettsiosial diseases.