Abstract: A method of extruding a coating or sheath onto an elongated support which comprises radially feeding the material into an inlet end of an extrusion head and decompressing, homogenizing, decompressing and compacting the material around a sleeve which surrounds the support. Then the material is expanded radially and then deposited in the form of a sheath on the elongated support. The plastic material flows under pressure and the sheath moves toward the exit pulling with it the elongated support on which it is deposited. In the final portion of the extrusion head the sheath is guided and pressed onto the support to form a homogeneous coating of predetermined thickness. The coated articles may have a tubular or rectangular profile or be in the form of ribbons, wires, or cables, and particularly coated cylinders which may be solid or hollow.