The 'Holy Trinity' Orthodox Cathedral (Romanian: Catedrala "Sfânta Treime" din Arad) is a Romanian Orthodox cathedral in Arad, in the Crișana region of western Romania.

Long before construction has ended, due to the specific of the church, bells were brought in from a foundry in Innsbruck, Austria.

[1] On the feast of Saint Nicholas, in 2008, the cathedral was inaugurated by the Patriarch of All Romania, Daniel.

A gathering of clergy and believers took part in the blessing of the church and its inauguration.

As the cathedral has been built, a temporary altar above the ground, but at the same time underneath the floor of the nave and subsequently under the main altar was used for celebrating liturgy, was blessed at the same time during the inauguration and kept as a permanent installation.