The purpose of our work was to conduct a survey of the horse population for the presence of parasites of the gastrointestinal tract in Moscow and the Moscow region. The research included horses aged 1.5 months to 26 years from horse farms and from private owners too. Fecal samples were collected rectally from 571 horses and were examined on the day of collection by flotation method and sedimentation method. Horses are infected with parasites of the gastrointestinal tract by 47.5% in the Moscow region. The main representatives of the parasite fauna are nematodes. Strongylidae gen. sp. (44%), Parascaris sp. (10.3%), Oxyuris equi (1.4%), Eimeria leuckarti (0.5%) were found. Statistically revealed correlations between the level of infection and the age of the horse (p < 0.001), as well as between the level of infection and the conditions of keeping (p < 0.001). The most infected were horses in the age group from 1 to 3 years. According to the study, herd horses are significantly more likely to be infected with Parascaris sp. and O. equi. No correlation was found between the level of infection and the type of farming (horse farms or private owners) (p = 0.252).