Abstract: This invention relates to a replaceable eye-protecting lens system for breathing masks that is easy to handle and ensures a firm and safe, i.e. gas-tight fit of the lenses in the body of the mask. It is the object and problem of this invention to create a replaceable eye-protecting lens system that provides a wide field of vision for the person wearing the mask and ensures a mechanically firm and gas-tight fit of mask body and lens. This problem is solved according to the invention by creating a replaceable lens system for breathing masks wherein a groove-shaped holding fixture 5 is placed on the rim of eye-protecting lens 1 which holds a fastening element 2 of the mask body and a locking ring 4.