| Official Name: | Ugnasay |
| Native Name: | Угнасай |
| Settlement Type: | Ulus |
| Pushpin Map: | Russia Buryatia#Russia |
| Subdivision Type: | Country |
| Subdivision Name: | Russia |
| Subdivision Name1: | Republic of Buryatia |
| Subdivision Name3: | Kurumkansky District |
| Subdivision Type4: | Municipality |
| Utc Offset1: | +8:00 |
| Coordinates: | 54.5°N 150°W[1] |
Ugnasay (ru|Угнасай) is a rural locality (an ulus) in Kurumkansky District, Republic of Buryatia, Russia. The population was 35 as of 2010.[2]
Ugnasay is located 45 km northeast of Kurumkan (the district's administrative centre) by road. Maysky is the nearest rural locality.[3]