Family name St Cyr (St Cyr 
) , in all the world, is quite a rare surname. The surname St Cyr is characteristic of Canada, where it is quite a rare surname, Trinidad and Tobago, and the United States, where it is a rare surname. Measured by absolute frequency, it most frequently occurs in the United States, Canada, and the Dominican Republic.
| VARIANT | COUNTRY |
|---|---|
| St Cyr | Canada, Dominican Republic, United Kingdom, United States, Trinidad and Tobago |