The Balkan donkey, Equus asinus, is an endangered indigenous breed that was once found in the wider area of the Balkan Peninsula, especially in the hilly and mountainous areas of Serbia. It is estimated that today there are about 1,000 of them left, mostly in animal genetic resources breeding centers. They are characterized by exceptional resistance to disease and, to date, have not been subject to disease prevention measures, including parasite control. Herein, we examined parasite species richness and prevalence of endoparasites in 60 adult donkeys of both sexes from 3 sites: Stara planina Nature Park (a mountainous region corresponding to the original habitat where this species was once bred); Zasavica Special Nature Reserve (a plain area at the mouth of the Zasavica in the Sava River), and Krčedinska ada (a marsh island on the Danube River near Novi Sad). We found the most prevalent parasites were Dictyocaulus arnfieldi (68% at Stara planina and 100% at the other 2 sites); Trichostrongylus axei (38% at Stara planina, 57% at Zasavica, and 86% at Krčedinska ada); Strongylus vulgaris (32% at Stara planina and 435% at Krčedinska ada); and Strongylus edentatus (57% at Zasavica and 14% at Krčedinska ada). In addition, we found Cyathostomum spp., Anoplocephala spp., Eimeria leuckarti, and Eimeria solipedum in smaller numbers.