A cross-sectional parasitologic survey of a population of wild sifaka (Propithecus verreauxi verreauxi) was conducted at the Beza Mahafaly Special Reserve in southwest Madagascar. Ninety fecal samples were collected from thirty 1- to 30-yr-old male and female sifakas, and the formalin-preserved and polyvinyl alcohol–preserved specimens were examined using the zinc sulfate flotation and formalin-ethyl acetate sedimentation techniques. No intestinal parasites were recovered, possibly because the sifakas are arboreal in a dry, riverine habitat and lack human contact. Low rates of parasitic infection may have contributed to the evolution of later age at first reproduction and longer reproductive lifespan, for body mass, in Propithecus compared with other placental mammals.