The new shielding effectiveness (SE) measurement methodology basing on HPEM- RF DS110 pulse generator is described. In order to conduct validation of research methodology the shielding effectiveness measurement results for selected enclosure are presented. During the measurement the worked out methodology was used. The obtained measurement results are compared to shielding efficiency measurement results which are obtained using standard measurement methodology basing on the selective measurement receiver and RF signal generator which is used as source of testing signal.