This paper describes experiments in which high purity copper single crystals of two different orientations were processed for one pass by equal-channel angular pressing (ECAP) and the deformed structures were examined using optical microscopy (OM), orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). The first single crystal (0 degrees specimen) was oriented within the entrance channel of the die so that the ( I I I) slip plane and the < 110 > slip direction were parallel to the theoretical shear plane and shear direction, respectively. The second crystal (20 degrees specimen) was oriented with the {111} slip plane and the < 110 > slip direction rotated by 20 degrees in a clockwise sense from the theoretical shear plane and shear direction, respectively. For the 0 degrees specimen, after passing through the shear plane there were two crystallographic orientations representing the initial orientation and an orientation rotated by 60 degrees in a counter-clockwise sense from the initial orientation. For the 20 degrees specimen, there was an orientation rotated by 20 degrees in a counter-clockwise sense from the initial orientation after passing through the shear plane.