The Malankara Mar Thoma Syrian Church, often shortened to Mar Thoma Church, and known also as the Reformed Syrian Church and the Mar Thoma Syrian Church of Malabar, is an autonomous Oriental Protestant Christian church based in Kerala, India. While continuing many of the Syriac high church practices, the church is Protestant in its theology and doctrines. It employs a reformed variant of the West Syriac Rite Divine Liturgy of Saint James, translated to Malayalam.

The Mar Thoma Church sees itself as continuation of the Saint Thomas Christians, a community traditionally believed to have been founded in the first century by Thomas the Apostle, who is known as Mar Thoma (Saint Thomas) in Syriac and describes itself as “Apostolic in origin, Universal in nature, Biblical in faith, Evangelical in principle, Ecumenical in outlook, Oriental in worship, Democratic in function, and Episcopal in character”.