The durability of high impact polystyrene (HIPS) as food packaging of dairy products was studied. Samples cut from container made from HIPS were exposed to different weathering conditions for 25, 50, 75 and 100 hours and with two stages tests before and after being used in food packaging using artificial aging in Xenontest-150 device. Three mechanical properties, tensile strength, elongation at break and impact strength were measured before and after the exposure to UV radiation. In general all mechanical properties decrease with time of exposure to UV light. Embrittlement of HIPS with consequent loss in mechanical strength was observed after testing the weathered HIPS with different method, mechanical, thermal and optical techniques. The chain scission was confirmed using the IR spectroscopy technique. Deformation in structure of HIPS was detected by examining the morphology of the sample using polarizing microscope. Two techniques were used for the determination of styrene migrants, gas-liquid chromatography (GLC) and high performance liquid chromatography (HPLC)