Chagas' disease, or American trypanosomiasis, caused by the hemoflagellated protozoan Trypanosoma cruzi (class Zoomastigophorea and family Trypanosomatidae), is the leading cause of dilated cardiomyopathy in man. In dogs in North America, Chagas disease mainly occurs in working dogs in southeastern Texas. It is likely that most dogs become infected by eating infected vectors, causing the release of the organisms into the mouth of the host. Most dogs are diagnosed during the chronic stage of the disease, which is typified by dilated cardiomyopathy and malignant ventricular-based arrhythmias. This article reviews the etiology, epidemiology, pathogenesis, diagnosis, and available therapy for Chagas' disease in dogs.