Cognomen Oandasan (Oandasan 
) , all around the world, is quite a rare last name. The family name Oandasan is habitual in Philippines, where it is quite a rare surname, Saudi Arabia, where it is a rare surname, and Ireland. Not in comparison with a country's population, it is the most numerous in Philippines, the United States, and Saudi Arabia.
| VARIANT | COUNTRY |
|---|---|
| Oandasan | Saudi Arabia, Philippines, Ireland, United States, Canada |
| william oandasan American writer, US (b. 1947) |
|