Lachung is a town and hill station in northeast Sikkim, India. It is located in the North Sikkim district near the border with Tibet. Lachung is at an elevation of about 9,600 feet (2,900 m) and at the confluence of the Lachen and Lachung Rivers, both tributaries of the River Teesta. The word Lachung means "small pass". The town is approximately 125 kilometres (78 mi) from the capital Gangtok.
The Indian Army has a forward base in the town. Before the Chinese annexation of Tibet in 1950, Lachung was a trading post between Sikkim and Tibet, after which it was closed down. The town's economy has been boosted by tourism in recent years as the region has been opened up by the Indian government. Tourists come from all over the World to visit the town between October and May, mostly on their way to the Yumthang Valley and the Lachung Monastery. Most of Lachung's inhabitants are of Lepcha and Tibetan descent. Languages spoken here are Nepali, Lepcha and Bhutia. During winter the town is usually covered in snow. Lachung is also the base camp for Rhododendron Valley Trek which starts from Yumthang Valley and ends at Lachen Valley.
Lachung has been described as the "most picturesque village of Sikkim" by British explorer Joseph Dalton Hooker in his definitive, The Himalayan Journal (1855). Skiing is conducted in Phuni near this town.