The aim of this study was to determine the frequency of Toxoplasma infection in wild mammals, particularly noncarnivorous species, and to identify possible sources of infection for humans. A serological study was conducted that included 310 animals representing 10 species of terrestrial mammals from the same region (primary tropical rain forest inhabited by humans). Toxoplasmosis was diagnosed using a direct agglutination test using formalin-treated Toxoplasma gondii. The prevalence of antibodies for toxoplasmosis differed greatly between species and ranged from 0% to 62%. The seroprevalence of toxoplasmosis was zero or very low for tree-dwelling animals, which included sloth, porcupine, and howler monkey. Conversely, the prevalence of infection was 46-62% among granivores, insectivores, and burrowing animals, such as peccary, paca, and armadillo. We conclude that wild mammals in French Guiana constitute a reservoir of T. gondii parasites. Given the absence of domestic cats from the forest, noncarnivorous species may be infected by the ingestion of oocysts that are eliminated into the soil or water in the stools of wild cats and then dispersed.