A seroepidemiological survey of toxoplasmosis was carried out in Niamey, Niger, in 1992. Three hundred and seventy-one sera from 200 females and 171 males were tested by indirect immunofluorescence assay for IgG. Using a cut-off value of 12 UI, 67 sera (18%) were positive. In this group detection of specific IgM by ELISA with immunocapture revealed 8 positive sera (11.9%). Seroprevalence of specific IgG was not correlated with ethnic origin or sex but did increase with age from 6.9% in subjects under 5 years to 34.9% in subjects 50 years and over. These findings are comparable with those from previous studies in similar climates and confirm that the prevalence of toxoplasmosis is higher in humid coastal regions than dry desert areas.