Eugen has name days listed for March 4, May 2, May 21, and June 2 in Croatia, June 17 in Estonia, November 5 in Sweden, November 13 in Austria, November 18 in Slovakia, and December 19 in Croatia.
Eugen is a name heard infrequently in the modern USA, suggesting a classic or perhaps an older immigrant background association. Its origin lies in ancient Greek terminology suggesting noble lineage or good birth. The gender classification for Eugen is decidedly masculine across most international contexts. The overall tone imparted by the name is one of elegant dignity and established character. It generally avoids modern naming trends, sticking to a more timeless appeal. This name carries a sense of formal, cultivated bearing.
| Country | Day | Month | Names |
 Poland | 4 | January | Angelika, Aniela, Benedykta, Benita, Dobromir, Dobrymir, Eugeniusz, Grzegorz, Izabela, Leonia, Rygobert, Tytus |
 Spain | 4 | January | Eugenio |
 Ukraine | 21 | January | Candid, Candida, Candace, Eugene, Yaroslav, Slavko |
 France | 7 | February | Eugénie |
| Poland | 4 | March | Adrian, Adrianna, Arkadiusz, Arkady, Eugeniusz, Kazimierz, Lew, Łucja, Lucja, Lucjusz, Wacław, Wacława |
| Spain | 4 | March | Francisca, Arcadio, Casimiro, Eugenio |
| Poland | 6 | March | Eugenia, Felicyta, Frydolin, Jordan, Klaudian, Koleta, Róża, Wiktor, Wiktoriusz, Wojsław |
 Lithuania | 2 | June | Aukse, Azuolas, Erazmas, Eugenijus |
| Poland | 2 | June | Efrem, Erazm, Eugeniusz, Marcelin, Maria, Marianna, Mikołaj, Nicefor, Piotr, Racisław |
| Poland | 8 | July | Adrian, Adrianna, Chwalimir, Edgar, Elżbieta, Eugeniusz, Kilian, Prokop, Wirginia |
| France | 13 | July | Enzo, Eugène, Henri, Joël |
| Poland | 13 | July | Ernest, Ernestyn, Eugeniusz, Irwin, Jakub, Justyna, Małgorzata, Radomiła |
| Spain | 13 | July | Eugenio, Sara, Joel |
 USA | 23 | August | Eugene, Eugenia, Geena, Gena, Gene, Genie, Gina, Jina, River, Zaccheus |
| Poland | 6 | September | Albin, Beata, Eugenia, Eugeniusz, Magnus, Michał, Uniewit, Zachariasz |
| Poland | 13 | September | Aleksander, Aureliusz, Eugenia, Filip, Lubor, Materna, Morzysław, Szeliga |
| Lithuania | 15 | September | Eugenija, Nikodemas, Rimgaile, Vismantas |
| Poland | 16 | September | Antym, Cyprian, Edda, Edyta, Eufemia, Eugenia, Franciszek, Jakobina, Kamila, Kornel, Lucja, Łucja, Sebastiana, Sędzisław, Wiktor, Wiktoriusz |
 Slovakia | 18 | September | Eugénia |
| Poland | 13 | November | Arkadiusz, Arkady, Brykcjusz, Eugeniusz, Jan, Mikołaj, Stanisław, Walentyn |
 Estonia | 23 | December | Eugenia, Senna, Senni |
 Greece | 24 | December | Evgenia, Ahmet, Eugenia |
| Ukraine | 24 | December | Eugenia |
 Austria | 25 | December | Anastasia, Eugenia, Josefina, Therese |
 Hungary | 25 | December | Eugénia |
| Lithuania | 25 | December | Eugenija, Gene, Grazvydas, Sanrime |
| Poland | 25 | December | Anastazja, Eugenia, Piotr, Spirydion |
| Spain | 25 | December | Belén, Eugenia, Natividad |
 Italy | 30 | December | Eugenio |
| Poland | 30 | December | Dawid, Dawida, Dionizy, Eugeniusz, Irmina, Katarzyna, Łazarz, Rainer, Sabin, Sewer, Uniedrog |
Croatia 
Sweden