Family name Ostafiychuk (Остафийчук 
, Ostafiychuk 
) , in the entire world, is a rare last name. The last name Ostafiychuk is characteristic of Kazakhstan, where it is a rare surname, Belarus, and Russia. Not in comparison with a country's population, the name is most common in Russia, Kazakhstan, and Spain.
| VARIANT | COUNTRY |
|---|---|
| Остафийчук | Romania, Ukraine, Kazakhstan, Belarus, Russia |
| Ostafiychuk | Ukraine, Spain, Bulgaria, Italy, United States |