The Open de Oeiras is a professional tennis tournament played on clay courts.

It is currently part of the ATP Challenger Tour.

It was first held in Oeiras, Portugal during 2021.

[1] The winning records are held by Portuguese tennis players both in singles and doubles, by Gastão Elias, and by Nuno Borges and Francisco Cabral respectively, with 3 victories each.

They recorded them simultaneously two times in the 2022 I and II editions, making them one-flag winners editions.