Abstract For centuries, the yak and its hybrids with domestic cows (dzomo/dzo) have been contributing to the socio-economic status of their owners in desolate regions of the Greater Himalayas. Studies on the prevalence of parasitic diseases in these animals were undertaken in Ladakh (Jammu and Kashmir), Sikkim and villages near the Indo-Nepal border of Uttar Pradesh. Visceral organs of necropsied animals were observed for the presence of adult metazoan parasites, fresh or preserved faecal samples were examined for the eggs of helminth parasites and protozoan cysts, and blood smears were examined for haemo-protozoa and microfilariae. In all, examination of 225 faecal samples, 180 blood smears and the visceral organs of thirteen yaks and dzomo/dzo was undertaken. On necropsy, vesceral organs revealed various adult liver and stomach flukes, gastrointestinal nematodes, tapeworms, cysts of Coenurus spp. and hydatid cysts, as well as Setaria cervi worms and large and/or small sized Sarcocystis cysts. On coprological examination, egg prevalences of 10% for Fasciola spp., 6.6% for various amphistomes, 10% for Moniezia spp., 76.4% for Strongylate spp., 24% for Neoascaris spp. and 13.7% for Nematodirus spp. were recorded. Identification of infective larvae from the faecal cultures showed that a majority of eggs (86.3%) in the host faeces were contributed by nematodes belonging to Trichostrongyle spp., Ostertagia spp. and Cooperia spp. This was followed by Chabertia spp. (6.5%). Haemonchus spp., Bunostomum spp. and Nematodirus spp. together contributed only 7.2% of the eggs found. Among protozoan infections, Eimeria brasiliensis and E. zurnii were common. None of the blood smears evidenced any haemoprotozoa or microfilariae. Likewise, none of the animals were positive for Trichuris spp. All animals were positive for one or more species of parasites. An immediate need to undertake systematic studies on the health problems of yak is stressed in order to save this species from extinction.