The cycloposthiid ciliate Cycloposthium edentatum Strelkow 1928 is redescribed from the stomach content of the black-striped wallaby, Macropus dorsalis (Gray) following protargol staining and light and electron microscopy. This is the first record of a cycloposthiid ciliate occurring in a marsupial, as all previous records have been restricted to eutherian herbivores, especially equids. C. edentatum was found in 7 (39%) of 18 black-striped wallabies examined, but not in any of 263 animals belonging to another 20 macropodid species examined. C. edentatum is distinguished by the form of the macronucleus, the presence of a longitudinal pellicular groove, a broad posterior tail and pellicular patterning. C. edentatum specimens recovered from M. dorsalis were smaller than those reported from horses, being up to 50% shorter and 42% thinner.