The purpose of this study was to determine the prevalence of toxoplasmosis in samples of healthy populations in Ivory Coast. Various factors have been studied: age, sex, ethnic group, occupation, food, contacts with animals, climate. The samples were obtained in four places which were different by geographical situation and climate: Abidjan (urban site), Bonoua (littoral site), Bin-Houye (forest site), Odienne (predesert site). The samples of sera or blood were deposited on filter-papers and tested by latex agglutination (for IgG) and ISAGA (for IgM). Results were analysed by statistical methods. More than 2,000 samples have been studied, showing a prevalence higher in humid tropical zones (55.6% to 70%) than in predesert zone (37.2%). The first contact of the child with the parasite was more often before reaching 10 years but the risk for women was important until the age of 20. The other studied factors didn't appear to have any effect.