Bottled and powdered green tea beverages are currently very popular and are marketed to consumers by advertising the presence of naturally occurring antioxidants in the beverages. The antioxidants in green tea have been credited with such healthful benefits as inhibition of the growth of cancer cells, lowering of LDL cholesterol levels, and decreasing the risk of stroke and heart disease. The antioxidants found in green tea are polyphenolic compounds known as catechins. There are four major catechins found in green teas: (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), (-)-epicatechin (EC). Although many bottled and powdered green tea beverages advertise the presence of antioxidants, the packaging on very few of the beverages state the concentration of antioxidants in these beverages. Additionally, the majority of the scientific literature on quantative determination of catechin levels in green tea beverages focuses on freshly brewed or extracts of teas not on bottled and powdered teas. In this study, high-performance liquid chromatography with UV detection was used to screen fifteen commercially available bottled or powdered green tea beverages for the presence of the four major antioxidants and caffeine. A wide distribution of concentrations of caffeine and the four catechins were observed in the fifteen green teas analyzed. Also, no uniformity in the concentrations of caffeine and the four catechins were observed when the teas were compared.