Abstract: A counter-rotating turbine for a turbine engine comprising an inner rotor having an inner drum to which is attached a plurality of inner impellers rotatably supported by a first shaft, an outer rotor comprising an outer drum to which is fastened a plurality of outer impellers rotatably supported by a second shaft coaxial with the first shaft, the outer rotor comprising a downstream impeller having a plurality of downstream moving blades extending between an outer shroud and an inner shroud, one upstream end of the outer shroud being attached downstream of said outer drum, the inner shroud being attached to the second shaft, at least one of the inner shroud and of the outer shroud comprising at least one flexible transition part configured to allow elastic deformation of said shroud in the radial direction.