Red deer (Cervus elaphus) were introduced in southern Latin America about a century ago and characteristics of the invasion raise concerns over their epidemiological role for various diseases. We report on the possible occurrence of Taenia ovis krabbei established in a sylvatic cycle in Patagonia. Hook characters, size, appearance, and location of a cysticercus from a wild red deer are consistent with Taenia ovis ovis or T. o. krabbei. Although it is not possible to differentiate between T. o. ovis and T. o. krabbei on morphological grounds with certainty, several biological characteristics indicate the cysticercus may belong to T. o. krabbei. Red deer have been reported to be refractory to T. o. ovis infection whereas other potential intermediate hosts like cattle, goats, pigs and sheep have been shown to be refractory to T. o. krabbei. Other native ungulates sympatric with red deer in Patagonia include Lama guanicoe and the endangered huemul deer (Hippocamelus bisulcus). Possible or known definitive hosts include native felids like Puma concolor, Felis colocolo, F. guigna and canids like Dusicyon griseus, D. culpaeus, and domestic dogs.