The improvement of the quality of railway rails is associated with the use of steels of a new generation, which differ from known steels, DSTU 4344:2004 and EN 13674:2011, with a higher level of alloying. The operational properties of railway rails made of structural steels primarily depend on the mechanical properties. In steels of the pearlite class, wear resistance is ensured due to the small distance between the pearlite plates that contributes to the increase in hardness. The development of railway rails of a new generation and the determination of the effect of heat-treatment regimes on the structural component of steel to obtain a high complex of mechanical properties is an actual direction of research. The goal of this work is the study of the microstructure and fine structure of finely-dispersed pearlite in steels for high-strength rails with hardness at the level of world requirements. Samples of experimental steel are studied, which were previously deformed and heat-treated according to experimental regimes, which differed in cooling rates from 0.52 to 5.1°С/s. Based on the analysis of the interlamellar distance, as established, all steels have a structure of sorbitol-like pearlite with an interlamellar distance of 0.09–0.20 $\mu$m. This result meets the NTD requirements for the structure of thermally strengthened rails (DSTU 4344:2004 and EN 13674:1-2011). Based on the results of the analysis after heat treatment of the test steels, as established, the microstructure is a highly-dispersed pearlite that meets the requirements of foreign standards. Test rail steel with 0.90% C, 0.39% Si, 0.89% Mn, 0.0003% B, 0.0006 Ca with increased carbon content has mechanical properties meeting the requirements of EN 13674:1-2011 (R400HT).