| Official Name: | Lajenu |
| Native Name: | لجنو |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | South Khorasan |
| Subdivision Type2: | County |
| Subdivision Name2: | Ferdows |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Eslamiyeh |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Borun |
| Population As Of: | 2006 |
| Population Total: | 42 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 34.2778°N 58.3378°W |
Lajenu (Persian: لجنو, also Romanized as Lajenū) is a village in Borun Rural District, in the Eslamiyeh District of Ferdows County, South Khorasan Province, Iran. At the 2006 census, its population was 42, in 11 families.