Characteristic parameters of a covered microstrip line with ground planes of finite width are determined using hybrid boundary element method (HBEM). This method, developed at the Faculty of Electronic Engineering of Niš is based on the combination of equivalent electrodes method (EEM) and boundary element method (BEM). Results for the characteristic impedance of the observed microstrip line are compared with the corresponding ones obtained by the finite element method. [Projekat Ministarstva nauke Republike Srbije, br. III 44004]