Surname Sienczewski (Sienczewski 
) , across the world, is a very rare cognomen. The family name Sienczewski is characteristic of Poland, where it is a rare surname, Australia, where it is a very rare surname, and Canada, where it is an extremely rare surname. In absolute terms, the name is most common in Poland, Australia, and Germany. Also, Sienczewski is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Sienczewski | Poland, Canada, Australia, Germany, United States |