Abstract Background Horses are used in various countries for multiple purposes and often play a crucial role in the livelihood of many communities. However, parasitic infections represent a significant threat to their health and productivity. Objectives:  This study aimed to identify gastrointestinal parasite species affecting horses using coprological methods and to assess the influence of certain factors (age, sex, and bioclimatic zone) on these infections. Study design: These samples were analyzed using flotation techniques to detect fecal parasitic forms (eggs, oocysts) and larvae. Methods: Between January and May 2024, fresh fecal samples were collected from 121 horses in Setif region (Northeastern Algeria). Prevalences were calculated for each gastrointestinal parasite and the influence of certain intrinsic (age, sex) and extrinsic (region) parameters on these prevalences was analyzed. We have found, namely Strongylus vulgaris (38.84%), Oxyrus equi (7. 44%), Parascaris equorum (24.62%), Anoplocephala spp. 6.61% and 5.79 were carriers of Eimeria leuckarti and 4.96% had Giardia duodenalis cysts Conclusions This study demonstrates that horses in the Setif region are commonly affected by gastrointestinal parasites, with a predominance of mixed infestations. Both helminths and protozoa were identified, with Strongylus vulgaris and Parascaris equorum being the most prevalent species. The variations in infestation rates across age groups, sex, and geographical zones highlight the influence of environmental and management factors.   Keywords : Horse, parasite, gastrointestinal, Algeria