Trypanosoma rangeli is an American trypanosome of medical importance, infecting a variety of sylvatic and domestic mammals in a wide geographical area in Central and South America. Unlike T. cruzi, the etiological agent of Chagas disease, T. rangeli is non pathogenic to the mammal host. Because T. rangeli and T. cruzi are found in the same mammalian hosts and share triatomine vectors and a significant portion of their antigenic coat, sngle and/or mixed infections may lead to misdiagnosis and confusing epidemiological inferences. T. rangeli is also heterogeneous in nature, showing distinct genetic lineages as determined by their kDNA organization. The presence (KP1+) or absence (KP1-) of a specific kDNA minicircle allows the determination of major phylogenetic lineages of this species. The current sequencing effort will address the genome of T. rangeli SC-58 strain, a prototype of KP1- parasites circulating in nature which has been extensively characterized by biological, biochemical, molecular and immunological approaches. Comparative analyses with T. cruzi and other parasitic kinetoplastid species will allow the assignment of putative biological functions and detailed studies on virulence factors.