The structural-phase state of the CoCrFeNi high-entropy alloy obtained by laser alloying of technically pure iron surface layers with a mixture of powders of pure elements Co, Ni, Cr in an equiatomic ratio was investigated by XRD, EDX and metallographic analyses. As shown, the formation of multicomponent substitutional solid solution based on f.c.c. lattice, which is typical for high entropy alloys in the surface layers during laser alloying took place. The influence of the atmosphere, in which alloying is carried out, on the processes of structure formation and phase composition of alloyed surfaces are analyzed. As determined, during laser alloying in the air exothermic oxidation processes occurs, which, as a result, lead to the formation of oxygen- and chromium-enriched areas on the peripheral areas of laser spots. Laser alloying in argon atmosphere provides a uniform distribution of all elements on the surface of the laser alloying zone.