About four million Syriac Christians, living in the South Indian State of Kerala with important diaspora in India and outside, are following East or West Syriac liturgical traditions. They are popularly known as St Thomas Christians, as they are believed to have been evangelized by the apostle Thomas. As these Christians were in intermittent relationship with the Syriac Christianity in Mesopotamia since the early centuries, they are also known as Syriac Christians. At least since the sixth century, perhaps fourth century, they were following East Syriac Liturgy. In the sixteenth century several East Syriac Prelates, both Catholics and non-Catholics, introduced the East Syriac liturgy in its final form. Since the middle of the sixteenth century nearly half of them are following the West Syriac liturgy. Their liturgical practices provide examples of liturgical conservatism and radical reforms. Now the liturgical texts have been translated into Malayalam, language of Kerala, and English, Hindi or other regional language for the use of the diaspora. However, Syriac is used by several clergy. Syro-Malabar liturgy is a highly latinised form of East Syriac liturgy, followed in the Eastern-Catholic community. Malankara Orthodox Church follows the liturgical rites of the Syrian Orthodox Church of Antioch. History of the Marthoma liturgy, a reformed version of the West Syriac liturgy and used by the Reformed group, is presented here for the first time for the students of Syriac Christianity and liturgy.