The theriofaunal list of wild bovids of the South-Eastern Altai includes the Altai mountain sheep (Ovis ammon ammon), as well as the Siberian mountain goat (Capra sibirica). The predominant types of farm animals in the Altai Republic are goats and sheep. Parasite fauna and the interchange between wild bovids and small cattle in these areas is not well understood. Samples were taken by employees of the Sailyugemsky National Park. At the department, V.L. Yakimov, ovoscopic and larvoscopic research methods were carried out. The calculation of the average number of eggs was carried out using a VIGIS counting chamber (VNIIP named after K.I. Skryabin). According to the results obtained, an analysis of cross-invasion was carried out. In wild bovids from 120 samples studied and in small cattle from 31 samples, endoparasites belonging to four large taxonomic groups were found: protists, trematodes, cestodes, and nematodes. In wild bovids from the group of nematodes, invasion with eggs of the genus Trichuris was established, according to morphological and morphometric characteristics, eggs of the ascarid type were found, eggs of nematodes of the order Strongylida, the genus Marshallagia, Nematodirella, Nematodirus spp., as well as larvae of the genus Protostrongylus were also found. From the group of trematodes, eggs of the species Hasstilesia ovis, as well as Dicrocoelium sp. From the group of cestodes, eggs of the genus Moniezia sp. From the group of protists, oocysts of the genus Eimeria spp. In small cattle, in contrast to wild bovids, nematodes of the genus Strongyloides sp. The number of cases of detection in small cattle of the nematode of the genus Protostrongylus sp. significantly lower than in wild bovids, and eggs of the strongylid type were more common. Also, no eggs of the trematode of the genus Dicrocoelium sp. Otherwise, the endoparasite fauna was similar to wild bovids. This study will help to compile a complete picture of the parasite fauna and cross-invasion of wild bovids and small cattle.