Articles such as vests, helmets and structural elements containing a network of ultrahigh molecular weight, high strength, high modulus polyethylene or polypropylene fibers. The fibers, and especially polyethylene fibers of 15, 20, 25, 30 or more g/denier tenacity, and 300, 500, 1,000, 1,500 or more g/denier tensile modulus impart exceptional ballistic resistance to the articles in spite of the melting points, e.g. 145.degree.-151.degree. C. for the polyethylene fibers and 168.degree.-171.degree. C. for the polypropylene fibers, which are high for these polymers, but substantially lower than the 200.degree. C. or more melting point previously thought necessary for good ballistic resistance.