Inhomogeneities delta(M) over bar ((r) over bar) of the net magnetization near the planar gain boundaries (GB) in grain-oriented silicon steel (similar to3% Si) sheets, which are magnetized along the rolling direction (RD) to induction from B = 1.70 T to saturation B-S = 2.0 T, are investigated experimentally. Computations of volume energy density f(m) of magnetostatic fields (H) over bar (m), associated with perturbations delta(M) over bar ((r) over bar) of the saturation magnetization M-S near the GB, were carried out using the scalar magnetic potential theory. Results of computations of the field < (H)over bar>(m) components and energy f(m) obtained for the GB dividing grains with (01 (1) over bar) orientation, are in agreement with the results of corresponding measurements.