The purpose of this study was to evaluate hippological differences between Jeju ponies and Jeju Pony crossbreds population. This is the first repot of the differences use an anhidrosis in Korean native horses. The precise prevalence of anhidrosis is unknown; however, it has been estimated that 6-20% of horses may be affected. However, there is no report about the incidence of the disease in pony breeds. We performed diagnosis by clinical signs (sweating) to investigate the incidence of anhidrosis in Jeju Ponies(n=340) and Jeju Pony crossbreds (n=536) at Jeju Race Park from July to September in 2012 as a way of find of hippological difference. Results of this study showed that 74 (21.8%) of the 340 examined Jeju Ponies and 61 (11.4%) of the 536 examined Jeju Pony crossbreds had anhidrosis. So, the former had almost two times higher than the later. Among 74 Jeju Ponies those had the disease, 50 were male (23.1%) and 24 were female (19.4%). Among 61 Jeju Pony crossbreds those had the disease, 22 were male (9.5%) and 39 were female (12.8). In Jeju Ponies, anhidrosis were most common in above the age of 5, followed by 4, 2, 3-years-old. For Jeju Pony crossbreds, the disease were most common in 2-years-old, followed by above the age of 5, 4, 3-years-old. In two breeds, 3-year-old animals were most rare respectively. There was no predilection of age and sex which is correlated with another study. In conclusion, the incidence of anhidrosis in the ponies were considerably similar foreign countries. However, the authors thought that causes of the difference of the breeds were origin and genetic differences.