Magnetic-field induced alignment of polyethylene is firstly reported. Isothermal crystallization of low molecular weight polyethylene samples, high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), from melting state was conducted under the magnetic-field of 2 or 10 T. Isothermal crystallization at the temperatures which induced effective self-seeding achieved alignment of polymer chains. The b axis of polyethylene unit cell was aligned parallel to the magnetic-field. Low viscosity and low crystallization rate of the polyethylene samples were favorable for high degree of the magnetic-field alignment. (C) 2012 Elsevier Ltd. All rights reserved.