Endoscopic examination of the upper respiratory tracts of 1, 008 thoroughbred racehorses clinically observed to cough or breathe noisily revealed high percentages of abnormal conformation of the epiglottis, pharyngeal lymphoid hyperplasia, elevation of the soft palate, dorsal displacement of the soft palate, and laryngeal hemi-plegia. These disorders were accompanied by complications in many of the horses and were more prevalent in young horses.