Abstract: Disclosed is a sealing device for a rotary shaft, including a seal mounted fixedly in a passage through which the shaft passes, providing a sealed barrier and consisting of a bearing ring with an external axial flange and a radial flange, and a sealing washer attached to the bearing ring, surrounds the axial flange and extends inward along that face of the radial flange that faces toward the outside, to end in a sealing lip bearing slidingly against the rotary shaft to be sealed, the sealing device also including a protective unit protecting against contaminants. The protective unit includes an additional ring which is secured to the rotary shaft, which is positioned on the exterior side of the seal, and which includes a radial flange which, in collaboration with the radial flange of the bearing ring of the seal, forms an annular structure of the chicane or labyrinth type.