| Sergelen District | |
| Native Name: | Сэргэлэн сум |
| Native Name Lang: | mn |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Mongolia |
| Subdivision Type1: | Province |
| Subdivision Name1: | Dornod Province |
| Area Total Km2: | 4,169 |
| Population Total: | 2198 |
| Population Density Km2: | 1.8 |
| Timezone: | UTC + 8 |
| Utc Offset: | +8 |
Sergelen (Mongolian: Сэргэлэн) is a sum (district) of Dornod Province in eastern Mongolia. In 2009, its population was 2,198.[1]
Khogne District, founded in 1931, and Kherlenbayan District, founded in 1946, were merged together in 1961 to form Sergelen District, centered on the slopes of Sergelen Kharat Mountain.[2]