A nanoperiodic crystalline/amorphous arrangement was homogeneously developed by tensile drawing and subsequent annealing of ultrahigh molecular weight polyethylene (UHMW-PE) lamellae, trapping a large number of molecular entanglements on their surfaces. Lozenge crystalline blocks 40 nm in edge appeared regularly packed, producing the meshlike amorphous channels 5 nm wide. A grid-rotation analysis based on transmission electron microscopy observations indicated characteristic bicontinuous arrangements of crystalline and amorphous phases. The results of the small-angle X-ray scattering measurements for the drawn sample also supported this unique phase packing model.