Equal-channel angular-extrusion (ECAE) may greatly alter polymer properties because it creates anisotropy in the microstructure. Tensile, fracture toughness, flexure, and ballistic impact tests were performed to quantify ECAE effects on polymethylmethacrylate (PMMA). Young's modulus increased by 5% for one process condition, while strength and elongation to failure remained the same or decreased. Fracture toughness improved by 178% under a one-pass condition. Ballistic impact resistance changes after molecular orientation by ECAE; the failure mode is along the weak planes formed by the first process. The process that subjects the specimen to a second extrusion with 180 degrees rotation produces more isotropic and ductile ballistic impact properties. (c) 2005 Society of Plastics Engineers.