The study was carried out to evaluate the impact of gamma irradiation on the physical parameters, microbial safety and the total polyphenolic content (TPPC) of Ceylon black tea (Camellia sinensis L.). Commercially available Broken Orange Pekoe Fannings (BOPF) black tea samples of 5 distinct brands (n=120) were irradiated at 0, 1, 2, 5, 10 and 30KGy doses using Co-60 gamma irradiator. Samples were analyzed for water activity (aw), color of tea and tea infusion, microbial safety and TPPC. Water activities of samples were within the range of 0.32 to 0.58 and no effect had been observed due to the irradiation. The mean value of L, b and E hunter parameters of tea infusion was increased where the "a" value was decreased with the increment of irradiation dose when compared to the control sample. High irradiation doses resulted in darker color of the tea infusion. Irradiated samples showed a significant reduction of the total plate count. After 5kGy dose, irradiated samples were in sterilized condition. Yeast and mould counts were gradually decreased with the irradiation dose. TPPC of tea leaves of both irradiated and non-irradiated samples ranged from 9.17- 37.98 GAE/240 ml and TPPC values were increased with the irradiation dose. Results conclude that 5kGy is the optimum dose for the effective microbial safety, preserving the physical parameters and TPPC of commercially available Ceylon black tea.