Cognomen Гаыдаычук (Гаыдаычук 
) , in all the world, is an extremely rare last name. The last name Гаыдаычук is habitual in Eastern Europe, particularly Russia, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Гаыдаычук | Russia |
Gaydaychuk, and Haydaychuk