Abstract: A method evaluating a measuring electron microscope, comprising the steps of setting such modes of operation of a microscope, that will be used for subsequent measurements of sizes and line edge roughness; introducing a test-object which has a known straight edge into a chamber of objects of the microscope; orienting the test object on a stage of the microscope; scanning the test object with an electron beam; obtaining an image of the edge of the test object and saving the image in a digital form; localizing the edge of the test object and saving the image in a digital form; localizing the edge of the test object on the image on each line of scanning; producing storing a set of values of a coordinate X(i) which correspond to a position of the edge of an i-th line of scanning; approximating the sets of values X(i) with a straight line; calculating deviations P(I) of coordinates X(i) from a straight line on each line of scanning; analyzing a set of values of the deviations ?(i); calculating an ?ave and a maxima