| Official Name: | Zeyn ol Din |
| Native Name: | زين الدين |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Razavi Khorasan |
| Subdivision Type2: | County |
| Subdivision Name2: | Mashhad |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Central |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Kenevist |
| Population As Of: | 2006 |
| Population Total: | 370 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 36.3333°N 59.7064°W |
Zeyn ol Din (Persian: زين الدين, also Romanized as Zeyn ol Dīn; also known as Zeyn od Din) is a village in Kenevist Rural District, in the Central District of Mashhad County, Razavi Khorasan Province, Iran. At the 2006 census, its population was 370, in 94 families.