This pristine wildlife sanctuary has been declared a UNESCO World Natural Heritage site on 13 December 1991. It covers an area of about 1,737,587 rai (2.780 square kilometers) and is part of a large area of National Parks and Wildlife Reserve spanning several Western Thai provinces, stretching until the border with Myanmar (Burma). In Uthai Thani, it spans the Amphurs Lan Sak, Ban Rai, Huai Khot, and extends into Amphur Um Phang in Tak province. The reserve also connects with Thung Yai Naresuan national Park in Kanchanaburi province, forming the largest protected wildlife area in mainland Southeast Asia.

Almost every kind of primeval forest and jungle found in Thailand is present in this mostly mountainous sanctuary, which is home to a large variety of wildlife, some of them very rare and endangered: wild red gaur, buffaloes, bulls, tapirs, leopards, wild elephants, bears, hornbills, deer, snakes, etc. Moreover, wild rhinoceros and tigers are also said to still roam the area. Also present are several nationally rare species of reptiles and amphibians, including the Indian Monitor, giant Asiatic toad and Asiatic giant frog. Combined, Thung Yai and Huay Kha Khaeng sanctuaries are home to 34 internationally threatened species, emphasizing it's conservation value.

Besides the large variety of wildlife, the sanctuary also boasts great abundance in flora, with the number of different botanical species outnumbering those in European forests. There are numerous species of wild orchids alone. Various rivers and streams ensure that the area remains verdant all year round.
Not only is Huay Kha Khaeng famous for its largely undisturbed primeval forest, the sanctuary is also a memorial for Seub Nakhasathien, one of the most outstanding figures in Thailand's recent history. Khun Seub was a true conservationist, protecting forests and wildlife with his life. He was the key person in making Thung Yai-Huay Kha Khaeng Wildlife Sanctuaries a World Heritage Site. On 01 September 1990, after several years of struggling against natural exploiters and paving the way to international recognition of the sanctuaries, he set up a shrine to worship the spirits of the rangers who sacrificed their lives to protect Huay Kha Kaeng Wildlife Sanctuary, and committed suicide. For more information, please visit: www.seub.or.th/seublife/seub-techique-eng.asp.
