Disclosed is a method of determining geometric errors in a machine tool or measuring machine having a mobile unit for moving a target within a measuring volume. The method includes the steps of generating a succession of laser beams in different directions by means of an interferometer, and, for each direction, moving the target into a number of points along the beam; measuring, by means of the interferometer, the abscissa of each of the points from an origin located along the direction of the beam; acquiring the coordinates of each of the points by means of the machine; and determining error parameters of the machine on the basis of the abscissas measured by the interferometer, and the coordinates of the points acquired by the machine.