Cognomen بلاج (Blaž 
, Blaj 
, بلاج 
) , in all the world, is quite a common family name. The surname بلاج is habitual in Romania, where it is quite a common surname, Slovenia, where it is quite a rare surname, and Moldova. Measured by absolute frequency, this name is the most popular in Romania, Iran, and Italy. Likewise, بلاج is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Blaž | Austria, Germany, Bosnia and Herzegovina, Slovenia, Croatia |
| Blaj | Romania, Moldova, Italy, United States, Slovenia |
| بلاج | Morocco, Iran |