The aim of this study was to investigate to the incidence of dorsal displacement of the soft palate (YDDD) seen in thoroughbred Arabian and English racehorses. The material of the study consisted of 400 purebred horses brought to the Elazığ hippodrome. The horses that were brought to the examination after training and race were taken into a horse stock. The aim of this study was investigate to the incidence of dorsal displacement of the soft palate seen in thoroughbred Arabian and English racehorses. In the endoscopic examination, the air sacs, epiglottis, larynx cartilages and soft palate were examined by entering the apparatus through the nasal ventral. During the examination, swallowing reflexes were performed and it was checked whether the soft palate was separated from the epiglottis. The YDDD disease in horses was determined as 32.8% in males, 25.0% in females according gender and 30.6% in Arabian horses and 28.5% in English horses according to breeds. No statistical difference was found in the incidence of the disease depending on gender and race. The incidence of horses according to age showed a linear increase from 3.6% to 76.2% with increasing age. It was found that the disease was more common in older ages. Horses diagnosed with YDDD were treated using the thermocauterization method, and it was observed that the horses achieved their previous performance. In conclusion, in this study conducted on 400 horses, it was determined that the incidence of this disease was 29.5% and its incidence increased with age.