The paper compares the geometrical surface structure of modelled tooth flanks of cylindrical gear obtained by a three dimensional simulation of gear generation with the geometrical surface structure of real gear obtained through chiselling by Fellows method. The paper presents the methodology of modelling tooth flanks of cylindrical gears in the CAD environment. The modelling consists in computer simulation of gear generation. The computer simulation of the gear generation was performed in the Mechanical Desktop environment. Metrological measurements of the real gear were carried out using a coordinated measuring machine and a profilometer.