| La Unión | |
| Settlement Type: | Department |
| Mapsize: | frameless |
| Coordinates: | 13.542°N -87.88°W |
| Subdivision Type: | Country |
| Subdivision Name: |  El Salvador |
| Established Title: | Created |
| Established Date: | 1865 |
| Seat Type: | Capital |
| Seat: | La Unión |
| Area Total Km2: | 2074.3 |
| Area Rank: | Ranked 3rd |
| Population Total: | 263271 |
| Population As Of: | 2013 |
| Population Density Km2: | auto |
| Population Rank: | Ranked 8th |
| Timezone: | CST |
| Utc Offset: | −6 |
| Area Code Type: | Calling code |
| Iso Code: | SV-UN |
La Unión (pronounced as /es/) is the easternmost department of El Salvador. Its capital is La Unión. It covers a total of and has a population of 263,200. The department was created on June 22, 1865, and the city of La Unión was made its capital. The Conchagua Temple was built in 1693 and it is one of tourist attractions of the department, as well as containing archeological ruins in Intipucá and Meanguera.
The most important agricultural products are coffee, grass, fruits, cocoa, oleaginous seeds, and sugar cane. The manufacturing of palm and tortoiseshell products, panela, mangrove extract, and fish. It also has reserves of gold, iron, barium, and mercury.