Abstract: The optimum conditions for compaction and rolling of UHMWPE reactor powders to prepare HIGH strength filaments and fibers are discussed. The comparative analysis of some reactor powders (of the same Mw but different specific surface area S) and with different drawability are presented. The structural changes with compaction and monolithization has been studied. High-strength filaments can be obtained only from powders with a high S value. It is established that three sequential deformation processes take place during compression of a powder pellet under increasing pressure in a closed volume. In the first step, the powder particles in a pellet are brought into closer contact and the pellet density increases. Upon reaching a sufficiently large number of contacts, this densification process ceases and the plastic deformation of individual grains becomes a dominating process. This very important stage features the formation of bonds between separate RP grains. As the pressure grows further, the material density increases due to the elastic deformation; this step does not contribute to the final density and strength of the RP pellet upon the pressure release. The average pore size (powder density) of the initial RP pellets is a critical parameter: the effective compaction under pressure takes place only for the RP samples with a powder density below 0.150 g/cm3. As concerns to further orientation drawing of sintered UHMWPE reactor powder, there is an optimal compression strain λpd , at which the limit draw ratio increases in a stepwise manner. (λpd=2,5) The different behavior observed upon monolithization of UHMWPE reactor powders is due to the specific morphological structure determined to a considerable extent by their synthesis conditions. It is assumed that at the certain conditions amorphous regions haves been formed by entangled tie molecules intervening neighboring crystallites. It is the presence of such regions that makes the grains of this powder harder and incapable to of plastic deformation and coupling to one another upon monolithization.