Observation of ferroelectric domain structure with a scanning electron microscope is realized after deposition of a thin film of AgCl on the studied surface of the crystal. The conditions of preparation and the determination of optimum thickness of the film are presented. The choice of correct accelerating voltage and intensity for the primary electron beam is also determined. The observation of antiparallel and perpendicular ferroelectric domains on BaTiO3, TGS and GASH crystals by this technics is presented. In the GASH crystals, a difference of contrast between the hexagone zone and its outside is also observed. For observation of ferroelectric domains this method shows some advantages in comparison with observations made in SEM without coating the crystals and in TEM by decoration technics; for example, the polarity of the domains and their distribution can be determined.