Mcrostructural evolution in low carbon steel, 5083 Al alloy, and pure Ti, each representing BCC, FCC, and HCP crystal structure respectively, during equal channel angular pressing (ECAP) was carefully examined in order to understand their deformation response associated with a formation of an ultrafine grain structure during processing. In low carbon steel and 5083 Al alloy, the grain refinement was achieved by a grain subdivision due to the operation of the multi slip systems. In pure Ti, twin played a major role for deformation during a single pass of ECAP, but slip contribution became significant with increasing the pressing strain.