Abstract Post-mortem examinations of 236 goats from all provinces in Mongolia were performed for the study of helminths in goats. Thirty-nine helminth species belonging to three classes, 14 families and 23 genera were found. Trichocephalus spiralis and Avitellina centripunctata are reported for the first time in goats in Mongolia. The prevalence and intensity of helminth infections are reported for three age groups of goats in four seasons and three geographic zones in Mongolia. Common helminth infections of goats in all zones of Mongolia were infections of Ostertagia, Marshallagia and Nematodirus. In addition, fecal samples of 15 kids, 15 yearlings and 15 adult goats were examined monthly for eggs. The highest number of eggs per gram (EPG) of feces was counted in March (average 1335.3±405.3) and the lowest count was in November (54±18.6).