Green tea is a famous beverage produced from the dry leaves of Camellia sinensis. It suggested that it has an important beneficial effect on human health. The present work aims to assess the total phenolic and flavonoids content and in vitro antioxidant, inhibition of oxidative DNA damage and antiproliferative activities of ethanolic green tea extract, as preliminary phase of our laboratory studies in vivo. Different methods were used; DPPH radical-scavenging, inhibition of lipid peroxidation, OH-scavenging activity and DNA damage inhibition assays. In addition to antiproliferative activity which was evaluated using xCELLigence RTCA instrument. The extract presented high levels of phenolic compounds (700μg±1 μg of gallic acid equivalent/mg extract), flavonoids (33.74±0.05 μg of quercetin equivalent/mg extract), and 18 phenols were identified using HPLC-TOF/MS analysis. In DPPH free radical-scavenging assay, the extract showed remarkable activity; IC50value 10.35±0.14 μg/ml and the highest percentage of the inhibition was 96% similar to vitamin C in the same concentration 25 μg/ml. On the other hand, it exhibited the inhibition of lipid peroxidation with IC50value 333.29±17.90 μg/ml. The OH-scavenging assay indicated that the ethanolic green tea extract had a significant effect on OH radical; IC50value 12.83±0.63 μg/ml compared to ascorbic acid which was 10±0.72 μg/ml. The extract also exhibited a completed protection of plasmid DNA against oxidative damage and an interesting antiproliferative activity against PC3 cells. The results of this study confirmed that this ethanolic green tea extract is a potent source of beneficial antioxidant and anticancer.