Last name Sieńczak (Sieńczak 
) , in the entire world, is a very rare family name. The family name Sieńczak is habitual in Eastern Europe, particularly Poland, where it is a rare surname.
| VARIANT | COUNTRY |
|---|---|
| Sieńczak | Poland |
| bronisław sieńczak (1947-2016), PL (b. 1947) |
|