A Study of physical properties of gamma irradiated polyvinyl chloride (PVC) formulated for electrical wire insulator was conducted by measuring tensile strength, elongation at break and gel content of the test specimens as a function of dose. Irradiation was done at the radiation dose ranging from 0 - 200 kGy in air, nitrogen gas, and vacuum. Tensile strength and elongation of the irradiated specimens both before and after accelerated aging in the air were found to decrease, whereas after irradiation in nitrogen and vacuum, there were no observable change, Gel content of specimens irradiated in air, nitrogen gas, and vacuum found to increase slightly with increasing radiation dose especially if the irradiation were done in nitrogen and in vacuum.