A turbine stage for a turbine engine, the stage including a nozzle and a wheel mounted inside a sectorized ring carried by a casing. The nozzle is attached to the casing and is retained axially downstream by bearing against an annular split ring. Each ring sector includes at its upstream end a member of C-shaped section that is engaged on the casing rail and that holds the split ring radially. A radially inner wall of the C-shaped member of each ring sector extends inside the split ring over an entire axial dimension thereof and its upstream end portion is engaged in at least one recess of the nozzle.