Methods of wide-angle X-ray analysis and transmission electron microscopy were performed to investigate structural and phase transformation occurring in polyamide-6 (PA-6) by combined solid-phase processing including extrusion through a conical die (ED) and the following equal-channel multiple-angular extrusion (ECMAE). It was shown that high level of plastic and strength characteristics of extruded PA-6 is determined by the formation of a duplex structure consisting of elongated disoriented fiber-like entities and fragmented globular formations. Conservation of high values of plasticity of deformed PA-6 is also controlled by the transition of the crystals of a-form to the crystals of ?-form with higher plasticity reserve. We have established rational technology parameters of PA-6 processing by ED-ECMAE processes (the deformation degree eED at ED, deformation intensity ?G and the value of accumulated deformation eECMAE at ECMAE). POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers