  We consider a motion of a weakly relativistic charged particle with an
arbitrary spin in central potential $e/r$ in terms of classical mechanics. We
show that the spin-orbital interaction causes the precession of the plane of
orbit around the vector of total angular momentum. The angular velocity of
precession depends on the distance of the particle from the center. The
effective potential for in-plane motion is central, with the corrections to
Coulomb terms coming from spin-orbital interaction. The possible orbits of a
quantum particle are determined by the Bohr-Sommerfeld quantization rule. We
give examples of orbits corresponding to small quantum numbers, which were
obtained by numerical integration of equations of motion. The energies of
stationary states are determined by spin-orbital interaction.
