The study of self-medication among animals-zoopharmacognosy-is founded on observations that suggest that wild animals use plants with specific biological properties that may be beneficial to them. To verify whether self-vermifugation occurs among Eulemur fulvus in the wild, we studied their feeding behavior in both the dry and humid forests of Mayotte (Comoros Islands). We used the focal individual sampling method over an annual cycle. We conducted a complementary study during the 2-mo mating season, via the scan sampling method (at 10-min intervals). Among the 29 plant species brown lemurs consumed, we tested 16 in vitro as antiparasitic agents on 3 experimental parasite models (Rhabditis pseudoelongata, Trichomonas vaginalis, Entamoeba invadens). We obtained crude extracts to be tested after 2 successive chemical extractions (ethyl acetate and methanol), and 7 of them, belonging to 4 different plant species, showed an antiparasitic property: lemurs consumed Annona squamosa and Mimusops comorensis in large amounts, but ingested Ixora cremixora and Syzygium jambos sporadically. The 4 plants were active on the flagellate but only one of them (Ixora cremixora) also demonstrated antinematode properties. Humans use 2 of the plants as intestinal antiparasitic agents in traditional medicine and include Nègre, Tarnaud, Roblot, Gantier, and Guillot numerous other plants in the diet. The relative lake of amoebas and flagellates in stools of Eulemur fulvus may be related to the consumption of plants with antiprotozoal properties. Nevertheless, in the absence of specific behavior that could be linked to a voluntary therapeutic action during our study, self-vermifugation in Eulemur fulvus remains elusive.