The protective tube comprises a plurality of warp-knitted threads that define a strip the longitudinal edges of which are in contact with or overlap each other, defining a substantially circular cross-section, wherein at least one of said threads is monofilament thread, characterised in that at least one of the threads is carried on two or more needles, forming a mesh at least every two passes and a maximum of every twenty-five passes.It gives the protective tube greater curvature than that of currently known tubes, closing completely without need for heating for the strip to acquire its tubular shape.