This is a historical and morphological study on the Korean horse which aims at an elucidation of its history, its origin and its lineage. With these aims in view, this study comprises observations on the history and production policies concerning horses in Korea and physical, splachnological and osteological comparisons between its male and female, between its mainland species and that of Chejudo, between its existing species and that of 40 years ago and, finally, between it and other species in mast Asia. The content of the present dissertation may be summarized as follows. 1. Historical observations on the Korean horse Historical records show that there were Korean horses distributed all over the territory of Korea, ranging from its northeastern area of Kokuryo and Ye down to its southern area, prior to about 2,300 years before the end of the neolithic age. This species was known to China as $quot;Kwahama$quot; or $quot;Samchokma$quot; (Three-foot horses), and was presumably derived from the small-sizes Tarpan species which was introduced to Korea along with the Skyto Siberian culture. During about the same period or a little later (that is, from the last period of the neolithic age onward), the medium-sized Mongolian species was introduced from the north. These two species continued to exist either homogeniously or mixedly, with the medium-sized species distributed in the north and the small-sized in the south of the country. In addition to those, continuous introduction of such northern species as the Mongolian and of the Arabian species led, through inter-mixture and acclimatization, to the formation of an indigenous species. The Korean horse had been used as a means of transportation and o agriculture and also as sacrifice and food, until, from the beginning of the historic age, it became the object of one of the most important policies of the state. After the beginning of Samguk-shidae (the period of Three kingdoms) the administration of horses established itself as an institution that belonged to the military. Thus the production of horses in Korea reached an apex during the earliest days of th: Chosun Dynasty. The export of wellbred horses to China in they form of barter and the political disorder after the middle of the dynasty, however, deteriorated production of horses, both in quantity and in quality. At present there are about 25,00 smell-sized horses, on the mainland and on Chejudo, being used for transportational and agricultural purposes. 2. Biometric observations on the horse on the Korean mainland To obtain the hitherto underfined biometric constant of the mainland species, the present writer has measured 117 horses, sampled from the central area (Seoul), the Yongnam arcs (Taegu) and Honam area (Iri), with the following results. The average withers height of female horses is 116.5 ㎝ and that of male 116.0 ㎝, while that of female horses on Chejudo is 113.2 ㎝ and that of male horses on the island 111.7 ㎝. This shows that there is no significant difference between female and male is their stature, but the mainland species has a larger stature than the Chejudo species with the statistical significant difference. The percentage of the body-length vs. the withers height in the case of its female is 103.4% and that in the case of its male 102.0%. And the withers height is lower than the croup height in both cases. The comparison of its withers height with its body-length shows that the mainland species belongs to the Duerst`s low square type with a difference of 4.0 ㎝ (in the female) and 2.4 ㎝ (in the male). Also it belongs to the work type with its low foresection and high hindsection. The fact that the mainland species has a larger stature than that of Chejudo bas presumably been resulted from better conditions in feeding and management of horses on the mainland and from the inflow of better horses into the mainland from Chejudo. 3. Physical comparisons between the existing mainland species and tha