The epitaxial crystallization of polyethylene (PE) on uniaxially oriented isotactic polypropylene (iPP) has been investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The cross-sectional morphology of the epitaxial interfaces of multi-layered samples prepared by a new preparation method has been observed with view direction parallel to the epitaxial interfaces. It is found that fairly oriented PE lamellae grow perpendicular to the iPP layers with nucleation initiation on the iPP surfaces.