M. : Science, 1968 - 480 s. The publication is the fourth volume widely known both here and abroad of the Course of Theoretical Physics by Academician L. D. Landau and Corresponding Member of the Academy of Sciences of the USSR E. M. Lifshitz . Part 1 of the book presents the relativistic theory of free particles, particles in the outer field, the theory of light scattering, the relativistic theory of perturbations and its application to electrodynamic processes. Part 2 of the book presents radiation corrections in electrodynamics, the theory of weak interactions and some questions of the theory of strong interactions.