Solid-state drawing of melt-crystallized, or gel(solution)-crystallized, polyethylene (PE) is well established as a means of producing high modulus high-strength fibres. Here, an alternative route, based on melt-processing, is reviewed and its merits are assessed. Contrary to expectation, melt processing of flexible chain polymers can directly yield oriented products with good mechanical properties, without the need for post-drawing in the solid state. The melt-processed PE can give a special microfibrillar composite morphology which results in good mechanical properties. The paper also reviews aspects of composites design by comparing these microfibrillar composites with traditional fibre composites and molecular composites.