The purpose of this study was the epidemiology of toxoplasmosis in Congo, Ivory Coast (IC), Niger, Centrafrican Republic, Zaïre. This statistical study was relied upon the search of IgG and IgM antibodies. In Niger, the risk connected with the first contact of the parasite was very low for children and young women, since only 2.6% of children under 15 years were carrying IgG and 5.4% of women between 15 and 30. In the other countries, the highest risk of first contact occurred before reaching 10 years and mostly between 5 and 9 (the IgG survey was confirmed by IgM survey). Nevertheless, IgM survey had indicated that for the young women there was a risk of first contact until reaching 20 years in IC and 30 years in Congo. A comparative study of antibodies developed among the couple mother-children was conducted in IC and Congo.