| Official Name: | Trumao |
| Subdivision Type: | Region |
| Subdivision Name: | Los Ríos/Los Lagos |
| Subdivision Type1: | Province |
| Subdivision Name1: | Ranco/Osorno |
| Subdivision Type2: | Municipality |
| Subdivision Name2: | La Unión/San Pablo |
| Subdivision Type3: | Commune |
| Subdivision Name3: | La Unión/San Pablo |
| Government Type: | Municipal |
| Leader Title: | Alcade |
| Population As Of: | 2017[1] |
| Population Total: | 208 (La Unión commune)/48 (San Pablo commune) |
| Timezone: | Chilean Standard |
| Utc Offset: | −04:00 |
| Timezone Dst: | Chilean Daylight |
| Utc Offset Dst: | −03:00 |
| Coordinates: | -40.3478°N -73.1794°W |
| Elevation M: | 7 |
| Area Code: | Country + town = 56 + 63 |
| Blank Name: | Climate |
| Blank Info: | Cfb |
Trumao is the name of two hamlets (Spanish; Castilian: caserío) in Chile each located in front of the other on the shores of Bueno River. The northern hamlet belong to the La Unión commune and the southern to San Pablo commune.
In 1820 Patriot Colonel Jorge Beauchef reached trumao with his troops. Beauchef noticed the local Mapuche-Huilliche attended church and had a command of Spanish enough to communicate. He was received in friendly terms and helped to cross the river by locals who also put at his disposal bullock carts. Beuchef reciprocated by giving the Mapuche-Huilliche liquor and indigo dye which he had brought with him for this end.[2] After his crossing at Trumao the small patriot army continued south achieving a victory over the royalist at the Battle of El Toro.
Trumao on the north side of the river had by 1899 a public school, a church or mission and a telegraph.[3] Diccionario Geográfico de la República de Chile (1899) mentions that houses "begun to gather in the place in 1854".[3]