Nowadays many kinds of foreign breed horse and Korean native Cheju horse are raised in Korea. Horse has complicated structure and function to maintain normal health, and to overcome severe condition during gallop at full speed. Sometimes the disease take a bad turn becuase of difficulty of correct diagnosis for horse disease. In recent times, horse farm for fattening and reproduction is gradually increasing. However, thoracic disease and abdominal disease are frequently occuring by defect in raising management. But the diagnosis of these kinds of disease is difficult by former diagnostic method. Ultrasonographic diagnostic method is a method to slove the problem. In abroad, nowadays ultrasonography has been reported for circulatory organs and abdomonal organs in horse, cattle, sheep, and dog, and the importance of ultrasonographic diagnosis is recognized in veterinary clinical medicine. In the country, ultrasonography of Korean native goat, cattle and dog was recently reported, but there was no report for the ultrasonography of horse. So, ultrasonogram for the thyroid glands, jugular vein and carotid artery was evaluated in Cheju horse and Thoroughbred horse. Thyroid gland, jugular vein and carotid artery were determined on both sides of neck. The length of right thyroid lobe at the Thoroughbred horse, Thoroughbred foul, Cheju horse and Cheju foul were 54.8, 45.1, 46.1 and 42.2 mm, respectively. The width of right thyroid lobe at the Thoroughbred horse, Thoroughbred foul, Cheju horse and Cheju foul were 18.1, 14.3, 14.6 and 14.2 mm, respectively. The height of right thyroid lobe at the Thoroughbred horse, Thoroughbred foul, Cheju horse and Cheju foul were 27.3, 25.6, 26.2 and 25.5 mm, respectively. Similar ultrasonographic measurements were obtained for the left thyroid gland. The internal diameter of left jugular vein at the Thoroughbred horse, Thoroughbred foul, Cheju horse and Cheju foul were 10.6, 9.7, 10.5 and 9.2 mm, respectively. Similar ultrasonographic measurements were obtained for the right jugular vein. The internal diameter of right carotid artery at the Thoroughbred horse, Thoroughbred foul, Cheju horse and Cheju foul were 9.5, 8.8, 9.1 and 8.5 mm, respectively. Similar ultrasonographic measurements were obtained for the left carotid artery. It is concluded that the ultrasonographic values of this study provides references for the diagnosis of morphologic changes in the thyroid gland, jugular vein and carotid artery in Korean native Cheju horse and Thoroughbred horse.