A growing interest in nanostructured materials brought about development of their fabrication methods. A great interest has been paid in this context to the methods of grain refinement which can be induced by plastic deformation. Hydrostatic extrusion was recently proposed as an alternative method of grain size reduction down to nanometer scale in metallic materials. The aim of the present contribution is to describe, in a systematic way, advantages of this processing method, such as the possibility of processing hard-to-deform materials and obtaining large dimesions products. Special attention was given to the role of hydrostatic pressure and the effectiveness of the process in terms of grain refinement and high angle grain boundaries formation. Limitations of hydrostatic extrusion, such as restriction on strain in one pass and morphological texture are also discussed together with possibilities of their overcoming.