Trypanosoma cruzi frequently infects wild mammals in the southern United States but little is known about the effect of the parasite on reservoir hosts such as the raccoon (Procyonlotor). To investigate this issue, 30 raccoons trapped on St. Catherine's Island (Georgia, USA) during September, 1994 were tested for T. cruzi infection by examination of wet mounts of fresh blood and by culturing blood in liver infusion tryptose medium. Thirteen animals (43%) were found to be infected with T. cruzi. Heart tissues from 10 of the infected raccoons and 4 uninfected raccoons were fixed, sectioned, stained and examined for the presence of parasites and evidence of tissue damage. One T. cruzi pseudocyst was found in cardiac tissue from the left ventricle of a female raccoon. In addition, Sarcocystis sp. sarcocysts and schizonts of Hepatozoon sp. were observed in heart tissue from seven of the T. cruzi-infected raccoons. Mild, multifocal and interstitial inflammation was observed in the heart tissues of all 10 of the infected animals. No evidence of T. cruzi pseudocysts or tissue damage was observed in heart tissue from C3H/HeJ mice infected with culture forms of the parasites isolated from raccoons. Our findings suggest that the T. cruzi parasites isolated from raccoons in Georgia are not pathogenic to this host or C3H/HeJ mice and may be of low virulence.