Helminthic infections are one of the most common problems that horses encounter, and they frequently result in poor body condition, which limits their work potential and efficiency. The present study was designed to investigate the prevalence, severity and predisposing factors (age, sex and breed) of gastrointestinal parasites of polo horses in Ibadan, Oyo state.  Faecal samples were collected from a total of 56 polo horses in Ibadan. The samples were analysed for the presence of gastrointestinal parasites (GIPs) using sodium chloride flotation technique. Parasites were identified using standard method and faecal egg count was estimated using the modified McMaster technique. The egg per gram (EPG) of infected horses was classified as light (50-799 eggs), moderate (800-1200 eggs), and severe (over 1200 eggs). Information on age, sex and breed were documented to establish their association with faecal egg count. An overall prevalence of 92.9% GIPs was observed. Four GIPs comprising of three nematodes which are Strongylus spp < em>, Strongyloides spp and Parascaris equorum and one protozoan Eimeria sppwas seen. Strongylus spp (89.3.1%) and Strongloides spp (3.6%) occurred as single infection while amixed infection of Strongylus spp with Parascaris equorum (1.8%); Strongylus spp with Strongyloides spp (1.8%), and Strongylus spp (1.8%) with Eimeria spp < em> were also seen. There was no association between the prevalence/EPG and age, sex and breed of horses. However, there was higher occurrence and severe infection in adults, females and exotic breeds of horses. There is high prevalence of severe gastrointestinal parasite infection in polo horses in Ibadan which often occurred in some instances as mixed infections.There is need for improved veterinary care, investigation of the efficacy of available anthelminthics and susceptibility of parasitesfor improved horse health and optimal performance.