The shielding effectiveness of an alternating magnetic field was studied experimentally and analytically by comparing shields made of grain-oriented silicon steel sheets with shields made of non-oriented silicon steel. Magnetic shielding in alternating fields became complex owing to anisotropic-frequency-dependent permeability and eddy currents. Shields with <100> axes cross-stacked showed higher shielding effectiveness and isotropic distribution. The analytical results obtained by 3-D FEM showed some discrepancies with the experimental results.