Lachung () is a town in northeast Sikkim, India. It is located in the North Sikkim district and is near the border with China. Lachung is at an elevation of about 9,600 ft or 3,000 m and at the confluence of the Lachen River and Lachung Rivers, tributaries of the River Teesta. The word Lachung means "small mountain". The town is approximately 125 km from the capital Gangtok.
The Indian Army has a forward base in the town. Before the 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. Tourist 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.