| Official Name: | Ust-Altasha |
| Native Name: | Усть-Алташа |
| Settlement Type: | Ulus |
| Pushpin Map: | Russia Buryatia#Russia |
| Subdivision Type: | Country |
| Subdivision Name: | Russia |
| Subdivision Name1: | Republic of Buryatia |
| Subdivision Name3: | Mukhorshibirsky District |
| Subdivision Type4: | Municipality |
| Utc Offset1: | +8:00 |
| Coordinates: | 51.0333°N 111°W[1] |
Ust-Altasha (Russian: Усть-Алташа; Buriat: Алташын Адаг, Altashyn Adag) is a rural locality (an ulus) in Mukhorshibirsky District, Republic of Buryatia, Russia. The population was 200 as of 2010.[2] There are 5 streets.
Ust-Altasha is located 65 km west of Mukhorshibir (the district's administrative centre) by road. Zurgan-Debe is the nearest rural locality.[3]