The aim of this study was to evaluate the parasitism by gastrointestinal protozoa in Didelphis albiventris (opossum) in the central region of Rio Grande do Sul state. Fecal samples from six free living opossums were collected for research of parasites. Samples were analyzed by the centrifugal-flotation method with zinc sulfate and parasites were identified microscopically based on (oo)cyst size and morphology. Cysts of Giardia sp. and oocysts of Cryptosporidium sp. and Eimeria sp. were observed in four of the six opossums. All four infected marsupials showed mild infection by protozoa. This is the first report of Giardia sp. in D. albiventris.