A study was made of the prevalence of Trypanosoma cruzi infection in armadillos at a site near New Orleans, Louisiana, where the flagellate was known to occur. Blood cultures, microscopic examination of blood, and direct agglutination tests on sera were employed in 80 armadillos. T. cruzi was isolated in culture from 23 of 80 animals; identity of the parasite was confirmed in mice inoculated with each of the isolates. Only 2 animals were positive by direct examination of blood. Serologic evidence of infection was obtained for the 23 animals that were positive by culture, and for at least 7 of those animals with negative or contaminated cultures. These results suggest that the armadillo is a reservoir of this zoonosis.