A group of Proechimys rats (family Echimyidae, subfamily Echimyinae( was experimentally infected with Trypanosoma evansi. The long-term chronic infection induced, and the nature of the tissue lesions encountered, point towards their possible use as laboratory models for the study of T. evansi infections. Comparisons were made with albino rats in which the flagellate produced a short-term infection following inoculation.