| Official Name: | Tatnak |
| Native Name: | تتنك |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Qazvin |
| Subdivision Type2: | County |
| Subdivision Name2: | Buin Zahra |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Dashtabi |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Dashtabi-ye Sharqi |
| Population As Of: | 2006 |
| Population Total: | 99 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 36.0361°N 49.9156°W |
Tatnak (Persian: تتنك, also Romanized as Tatnag) is a village in Dashtabi-ye Sharqi Rural District, Dashtabi District, Buin Zahra County, Qazvin Province, Iran. At the 2006 census, its population was 99, in 24 families. It was founded by Boukralfa in the middle of the 19th century.