Cognomen Гаидаичук (Гаидаичук 
) , around the globe, is an extremely rare family name. The cognomen Гаидаичук is characteristic of Eastern Europe, particularly Russia, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Гаидаичук | Russia |
Gaidaichuk, Gaydaychuk, Haidaichuk, and Haydaychuk