| Official Name: | Trtnik |
| Pushpin Map: | Slovenia |
| Pushpin Label Position: | right |
| Pushpin Map Caption: | Location in Slovenia |
| Subdivision Type: | Country |
| Subdivision Name: | Slovenia |
| Subdivision Type1: | Traditional region |
| Subdivision Name1: | Slovenian Littoral |
| Subdivision Type2: | Statistical region |
| Subdivision Name2: | Gorizia |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Tolmin |
| Area Total Km2: | 1.51 |
| Population As Of: | 2002 |
| Population Total: | 33 |
| Population Blank1 Title: | Ethnicities |
| Population Blank2 Title: | Religions |
| Coordinates: | 46.2101°N 13.962°W |
| Elevation M: | 655.8 |
| Footnotes: | [1] |
Trtnik (in Slovenian pronounced as /ˈtəɾtnik/, German: Trennich[2]) is a small village southwest of Podbrdo in the Municipality of Tolmin in the Littoral region of Slovenia.[3]