Structural distortions in nonpolar, particularly, in semiconducting silicon crystals, caused by constant electric field have been disclosed by means of X-ray interferometry. It was shown that in the field both the direction of moiré fringes and the frequency (period) are changed, and the moiré patterns disappear at values of potential difference in excess of 1.5 kV. The moiré pattern obtained under the action of electrostatic field is independent of the direction (polarity) of the field, the pictures for both the polarities being completely identical.