A series of oriented tapes has been prepared from the blends consisting of high-density polyethylene (HDPE), with isotactic polypropylene (PP) and ethylene-propylene block copolymer (EP(b)C). The mechanical properties and structure-morphology of blends were investigated using differential scanning calorimetry, polarizing microscopy, wide- and small-angle X-ray diffraction, and dynamic viscoelastometer. It is observed that blends are incompatible in the 20-80% blend composition range. The two p-relaxation peaks each of PE and PP component appear in the dynamic spectra of these blends. The two peaks, however, merge into a very broad, single relaxation peak at lower blend compositions (9 and 18% blends), indicating reasonably good compatibility between the two blend components. Variation of PP and EP(b)C content in blends with HDPE affects the melting and crystallization temperature, crystallinity, crystallite dimensions, and crystallite and amorphous phase orientation of blend components, which, in turn, affect the mechanical properties of drawn tapes.