The level of Toxoplasma gondii infection among the general population of the Democratic Republic of Sao Tome and Principe is unclear. The T. gondii infection status of inhabitants who visited National Central Hospital on Sao Tome Island was assessed by a latex agglutination test. The overall seroprevalence was 74.5% (120/161). No significant gender difference in seroprevalence was found between males and females. The older age group (> or =45 years) had significantly higher seroprevalence (80.0%, 28/35) than the younger age group (<15 years) (20.0%, 3/15) (chi(2)=16.04, P<0.001).