A serologic survey for Toxoplasma gondii in 18 free-ranging forest mammal species (n=456) in French Guiana was undertaken with a direct agglutination test. Serum antibody prevalence varied from 0–71%. The relationships between ecologic features of the species and seroprevalence were investigated. Terrestrial mammals were significantly more exposed to T. gondii than other mammals. This result is concordant with oral exposure to T. gondii related to ground dwelling behavior and/or carnivory.