In the article assessment methodology of shielding effectiveness of ventilation pan- els of small overall dimensions made in the form of honeycomb with the use of the computer simulation method has been presented. Methodology and description of simulation environment for measuring shielding effectiveness of ventilation panels by the method of computer simulation have been shown. Final effect of simulation software operation is characteristics of shielding ef- fectiveness of a tested ventilation panel in the frequency function. In order to conduct validation of simulation software values of shielding effectiveness for a selected ventilation panel obtained by the computer simulation method have been compared with results obtained due to tests in real laboratory conditions.