The inaccuracy of the magnetic-field integral equation (MFIE) discretized with the Rao-Wilton-Glisson (RWG) basis functions is discussed. The electric-field integral equation (EFIE) gives accurate results with the usage of RWG basis functions for the conducting surfaces with arbitrary planar triangulations. Two reasons i.e., logarithmic singularity in the field integration and solid angle expression in the MFIE, that lead to inaccuracy of the MFIE, are also discussed. It is found that the current distribution and the radar cross section (RCS) obtained by the MFIE does not perfectly match their counterparts obtained by the EFIE.