Shock compaction of AlMgSi0.5 was realized by using a LEXAN projectile with a velocity of 1655 m s(-1). The dynamic pressure in the zone of impact was 8 GPa in the sample in the target at room temperature. The sample consisted of spheres of two particle size fractions (100-200 mu m and 200-315 mu m) separated in layers th rough wh ich the same shock wave was passing. The appearance of non-porous interparticle contacts in the impact zone, with the content of melted areas up to 10% was detected in the case of the larger particle fraction only. Smaller particles had no tendency to form the strong interparticle contacts, not even in the first layers in the direction of the shock wave. TEM analysis showed the presence of an intensively deformed structure in the zone of the planar shock wave, as well as the structures with very poor signs of recovery and recrystallization in particle contact areas. The hardening effect of the shock wave was obvious, so that microhardness in the zone of the planar wave in larger particles had reached the value of 120 Hv, much higher than the microhardness of the initial powder (70 Hv).