[en] The properties of Rydberg atoms in electric and magnetic fields have been considerd. Stark effect in Rydberg atoms has been studied. Diagram of energy-level shifts of H and He atoms that has been obtained in the course of experiments is close to the one calculated with the quantum mechanics techniques. The Rydberg atom is shown to be an ideal system for studying the tunnel effect. The stark effect structure analysis, has shown that overlapping the levels of Rydberg atoms may be explained by a certain specific symmetry. Thus, the presence of such a symmetry allows one to assume that the atomic electron motion in a external magnetic field obeys a certain regularity, yet unknown