Equine Gastric Ulcer Syndrome (EGUS) is one of the most common causes of poor performance in the equine patient and affects more than 90% of Standardbred and Thoroughbred racehorses in training. Nowadays, the principal therapeutic options for EGUS treatment include antiacids such as histamine receptor antagonists and proton pump inhibitors. Recently, many studies concerning feed supplements to treat and prevent EGUS were carried out. The aim of the present study was to evaluate the efficacy of a natural feed supplement, administered for 30 days, as the only treatment for gastric ulcerations in sport horses in training. Seven horses were selected for the study on the basis of their gastroscopic evidence of erosive and ulcerative lesions of the gastric mucosa. Each horse received a natural feed supplement (Gastrocure, Institute Farmaceutico Candioli, Italy) registered for use in horses for 30 days. Gastroscopy was performed on day 0 (T 1 ), day 15 (T 2 ) and at the end of the treatment (day 30, T 3 ). Scores were assigned according to MacAllister method (score 0,1,2,3,4 for number of lesions and score 0,1,2,3,4,5 for lesion severity). Statistical analysis showed a strong evidence (p<0.01) of lower scores occurring at T 3 when compared to T1for both number and severity of gastric lesions. In conclusion, the administration of Gastrocure was effective in reducing the number and severity of ulcerative lesions in horses affected by EGUS.