Rhinolaryngoscopy was performed to examine the upper respiratory tract of 29 racehorses showing persistent signs of upper respiratory tract disease. The abnormalities encountered were pharyngeal lymphoid hyperplasia (PLH), laryngeal hemiplegia (LH) and nasal polyps. Twelve horses had PLH I. A small number of white follicles scattered over the dorsal wall of the pharynx was noted. PL II was observed in nine horses. Many small, white follicles with numerous, large, edematous pink follicles in the dorsal wall ofthe pharynx and near the level of the pharyngeal orifices of the guttural pouches were seen. One horse had PLH III. Numerous large, pink follicles were interspersed among a few, shrunken white follicles in the dorsal and lateral pharyngeal walls. One had PLH IV. Large, pink follicles were closely packed together all over the pharyngeal mucosa of this horse. Four horses were found to have LH. Two had LH II and the other two had LH IV. Asynchronous movement of the arytenoid cartilages was observed in LH II. The horses with LH IV had marked asymmetry of the arytenoid cartilages. The left arytenoid cartilage was longer and thinner and with a shorter vocal ligament than the right part. Roaring was the common clinical sign observed. Four horses had a smooth, pedunculated mass in the nasal cavity.