Cognomen San Justo (San Justo 
) , all over the world, is a very rare last name. The cognomen San Justo is habitual in Argentina, where it is a very rare surname, Spain, where it is an extremely rare surname, and Mexico. Very seldom, San Justo is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| San Justo | Peru, Argentina, Mexico, Spain |