Liturgy of St John Chrysostom, Op. 31 (Russian: Литургия Иоанна Златоуста), is a 1910 musical work by Sergei Rachmaninoff, one of his two major unaccompanied choral works (the other being his All-Night Vigil). The Divine Liturgy of St. John Chrysostom is the primary worship service of the Eastern Orthodox Church.[1]