The main aspects of pellet structure, which authors have analysed in this paper are: phase composition; features of element migration between phases; crystal size in individual phases and their mutual arrangement; porosity; zonality; metallurgical properties. The characteristic features, which determine pellet metallurgical properties. These include the nature of porosity and the structure (defects) of raw/green pellets, which are largely inherited by fired pellets. The influence of the silicate bond mineral composition decreases as the degree of beneficiation of the concentrate increases. Accordingly, as the concentrate iron content increases, the influence of fluxing on the pellet properties decreases. However, pellets from iron-rich concentrates are more prone to breakdown in a blast furnace or a direct reduction shaft furnace. In general, the trend towards higher iron content in concentrates going into pellet production is creating a new demand for research into pellet structure and properties - research and modification of pellets with iron oxide content of 95% and above. This requires solutions, which minimize the influence of stresses in a sintered mass during the magnetite-hematite phase transition; formation of an open pore system (assuming pellet fluxing), which ensures high pellet reducibility; finding optimal binder compositions, which form the structure of raw/green pellets with the minimum number of defects; application of additives and technical solutions, which increase the oxygen diffusion through the crystal lattice of pellet minerals to enhance its reducibility rate; and a number of other challenges. A focus on these challenges will effectively unlock the potential of the current trend towards higher iron content in concentrates.