Articles such as containers made of a crystalline olefin polymer having improved transparency and impact strength obtained by biaxially extending an extruded tubular body of said polymer at an orientation temperature below the melting point to attain an extension magnification ratio of at least 1.5 for each of longitudinal and lateral directions wherein said polymer is a statistical random copolymer of propylene and from 0.3% to 5.0% by weight ethylene having a melt index of 0.6 - 3.0 g/10 min. Optionally, from 0.03 to 0.20 part by weight of aluminum p-tert-butyl benzoate or sodium p-tert-butyl benzoate are added to 100 parts by weight of said copolymer.