Cognomen St. Laurent-Smyth (St. Laurent-Smyth 
) , in the world, is an extremely rare last name. The cognomen St. Laurent-Smyth is habitual in Northern America, particularly the United States, where it is an extremely rare surname. Parts of the name also exists independently as a last name St. Laurent, and a last name Smyth.
| VARIANT | COUNTRY |
|---|---|
| St. Laurent-Smyth | United States |