The invention relates to the investigation of materials by optical means, in particular to methods for measuring the size of micro-objects. The method for measuring the size of micro-objects consists in that the micro-object is illuminated with an interference raster with a known period, formed by the interference of laser beams B1 and B2, then the pre-enlarged image of the interference pattern is projected onto a micro-object hologram recording carrier, the micro-object is placed in the focal plane of the microscope lens on the hologram registration carrier, it is projected the magnified image of the micro-object overlaying the reference interference raster, formed by the laser beams B1 and B2, then the reconstructed image of the micro-object is projected onto a computer screen. The sizes of the micro-object are determined proceeding from the values of the recorded hologram of the interference raster with a known period.